Learning to Select, Track, and Generate for Data-to-Text

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Learning to Select, Track, and Generate for Data-to-Text
                                        ∗
                   Hayate Iso† Yui Uehara‡ Tatsuya Ishigaki\‡ Hiroshi Noji‡
 Eiji Aramaki†‡ Ichiro Kobayashi[‡ Yusuke Miyao]‡ Naoaki Okazaki\‡ Hiroya Takamura\‡
   †
     Nara Institute of Science and Technology ‡ Artificial Intelligence Research Center, AIST
       \
         Tokyo Institute of Technology [ Ochanomizu University ] The University of Tokyo
       {iso.hayate.id3,aramaki}@is.naist.jp koba@is.ocha.ac.jp
 {yui.uehara,ishigaki.t,hiroshi.noji,takamura.hiroya}@aist.go.jp
            yusuke@is.s.u-tokyo.ac.jp okazaki@c.titech.ac.jp

                         Abstract                                 In addition, the salient part moves as the sum-
                                                                  mary explains the data. For example, when gen-
    We propose a data-to-text generation model                    erating a summary of a basketball game (Table 1
    with two modules, one for tracking and the
                                                                  (b)) from the box score (Table 1 (a)), the input
    other for text generation. Our tracking mod-
    ule selects and keeps track of salient infor-                 contains numerous data records about the game:
    mation and memorizes which record has been                    e.g., Jordan Clarkson scored 18 points. Existing
    mentioned. Our generation module generates                    models often refer to the same data record mul-
    a summary conditioned on the state of track-                  tiple times (Puduppully et al., 2019). The mod-
    ing module. Our model is considered to simu-                  els may mention an incorrect data record, e.g.,
    late the human-like writing process that gradu-               Kawhi Leonard added 19 points: the summary
    ally selects the information by determining the
                                                                  should mention LaMarcus Aldridge, who scored
    intermediate variables while writing the sum-
    mary. In addition, we also explore the ef-
                                                                  19 points. Thus, we need a model that finds salient
    fectiveness of the writer information for gen-                parts, tracks transitions of salient parts, and ex-
    eration. Experimental results show that our                   presses information faithful to the input.
    model outperforms existing models in all eval-                   In this paper, we propose a novel data-to-
    uation metrics even without writer informa-                   text generation model with two modules, one for
    tion. Incorporating writer information fur-                   saliency tracking and another for text generation.
    ther improves the performance, contributing to
                                                                  The tracking module keeps track of saliency in the
    content planning and surface realization.
                                                                  input data: when the module detects a saliency
1    Introduction                                                 transition, the tracking module selects a new data
                                                                  record1 and updates the state of the tracking mod-
Advances in sensor and data storage technolo-                     ule. The text generation module generates a doc-
gies have rapidly increased the amount of data                    ument conditioned on the current tracking state.
produced in various fields such as weather, fi-                   Our model is considered to imitate the human-like
nance, and sports. In order to address the infor-                 writing process that gradually selects and tracks
mation overload caused by the massive data, data-                 the data while generating the summary. In ad-
to-text generation technology, which expresses the                dition, we note some writer-specific patterns and
contents of data in natural language, becomes                     characteristics: how data records are selected to be
more important (Barzilay and Lapata, 2005). Re-                   mentioned; and how data records are expressed as
cently, neural methods can generate high-quality                  text, e.g., the order of data records and the word
short summaries especially from small pieces of                   usages. We also incorporate writer information
data (Liu et al., 2018).                                          into our model.
   Despite this success, it remains challenging                      The experimental results demonstrate that, even
to generate a high-quality long summary from                      without writer information, our model achieves
data (Wiseman et al., 2017). One reason for the                   the best performance among the previous models
difficulty is because the input data is too large for             in all evaluation metrics: 94.38% precision of re-
a naive model to find its salient part, i.e., to deter-           lation generation, 42.40% F1 score of content se-
mine which part of the data should be mentioned.                  lection, 19.38% normalized Damerau-Levenshtein
     ∗
       Work was done during the internship at Artificial Intel-
                                                                     1
ligence Research Center, AIST                                            We use ‘data record’ and ‘relation’ interchangeably.

                                                              2102
        Proceedings of the 57th Annual Meeting of the Association for Computational Linguistics, pages 2102–2113
               Florence, Italy, July 28 - August 2, 2019. c 2019 Association for Computational Linguistics
Distance (DLD) of content ordering, and 16.15%         Graves et al., 2016). This module is often used
of BLEU score. We also confirm that adding             in natural language understanding to keep track
writer information further improves the perfor-        of the entity state (Kobayashi et al., 2016; Hoang
mance.                                                 et al., 2018; Bosselut et al., 2018).
                                                          Recently, entity tracking has been popular for
2     Related Work                                     generating coherent text (Kiddon et al., 2016; Ji
2.1    Data-to-Text Generation                         et al., 2017; Yang et al., 2017; Clark et al., 2018).
                                                       Kiddon et al. (2016) proposed a neural checklist
Data-to-text generation is a task for generating de-   model that updates predefined item states. Ji et al.
scriptions from structured or non-structured data      (2017) proposed an entity representation for the
including sports commentary (Tanaka-Ishii et al.,      language model. Updating entity tracking states
1998; Chen and Mooney, 2008; Taniguchi et al.,         when the entity is introduced, their method selects
2019), weather forecast (Liang et al., 2009; Mei       the salient entity state.
et al., 2016), biographical text from infobox in          Our model extends this entity tracking module
Wikipedia (Lebret et al., 2016; Sha et al., 2018;      for data-to-text generation tasks. The entity track-
Liu et al., 2018) and market comments from stock       ing module selects the salient entity and appropri-
prices (Murakami et al., 2017; Aoki et al., 2018).     ate attribute in each timestep, updates their states,
   Neural generation methods have become the           and generates coherent summaries from the se-
mainstream approach for data-to-text generation.       lected data record.
The encoder-decoder framework (Cho et al., 2014;
Sutskever et al., 2014) with the attention (Bah-       3   Data
danau et al., 2015; Luong et al., 2015) and copy
mechanism (Gu et al., 2016; Gulcehre et al., 2016)     Through careful examination, we found that in the
has successfully applied to data-to-text tasks.        original dataset ROTOW IRE, some NBA games
However, neural generation methods sometimes           have two documents, one of which is sometimes in
yield fluent but inadequate descriptions (Tu et al.,   the training data and the other is in the test or val-
2017). In data-to-text generation, descriptions in-    idation data. Such documents are similar to each
consistent to the input data are problematic.          other, though not identical. To make this dataset
   Recently, Wiseman et al. (2017) introduced          more reliable as an experimental dataset, we cre-
the ROTOW IRE dataset, which contains multi-           ated a new version.
sentence summaries of basketball games with box-          We ran the script provided by Wiseman et al.
score (Table 1). This dataset requires the selection   (2017), which is for crawling the ROTOW IRE
of a salient subset of data records for generating     website for NBA game summaries. The script col-
descriptions. They also proposed automatic evalu-      lected approximately 78% of the documents in the
ation metrics for measuring the informativeness of     original dataset; the remaining documents disap-
generated summaries.                                   peared. We also collected the box-scores associ-
   Puduppully et al. (2019) proposed a two-stage       ated with the collected documents. We observed
method that first predicts the sequence of data        that some of the box-scores were modified com-
records to be mentioned and then generates a           pared with the original ROTOW IRE dataset.
summary conditioned on the predicted sequences.           The collected dataset contains 3,752 instances
Their idea is similar to ours in that the both con-    (i.e., pairs of a document and box-scores). How-
sider a sequence of data records as content plan-      ever, the four shortest documents were not sum-
ning. However, our proposal differs from theirs        maries; they were, for example, an announcement
in that ours uses a recurrent neural network for       about the postponement of a match. We thus
saliency tracking, and that our decoder dynami-        deleted these 4 instances and were left with 3,748
cally chooses a data record to be mentioned with-      instances. We followed the dataset split by Wise-
out fixing a sequence of data records.                 man et al. (2017) to split our dataset into train-
                                                       ing, development, and test data. We found 14 in-
2.2    Memory modules                                  stances that didn’t have corresponding instances in
The memory network can be used to maintain             the original data. We randomly classified 9, 2, and
and update representations of the salient informa-     3 of those 14 instances respectively into training,
tion (Weston et al., 2015; Sukhbaatar et al., 2015;    development, and test data. Finally, the sizes of

                                                   2103
T EAM     H/V W IN L OSS P TS R EB A ST F G P CT F G 3 P CT . . .                          The Milwaukee Bucks defeated the New York Knicks,
                                                                                                    105-104, at Madison Square Garden on Wednesday. The
         K NICKS     H    16     19   104 46    26        45         46       ...                   Knicks (16-19) checked in to Wednesday’s contest looking
         B UCKS      V    18     16   105 42    20        47         32       ...                   to snap a five-game losing streak and heading into the fourth
                                                                                                    quarter, they looked like they were well on their way to that
                                                                                                    goal. . . . Antetokounmpo led the Bucks with 27 points, 13
P LAYER                           H/V P TS R EB A ST B LK S TL M IN            C ITY        ...     rebounds, four assists, a steal and three blocks, his second
                                                                                                    consecutive double-double. Greg Monroe actually checked
C ARMELO A NTHONY        H 30 11     7   0   2                       37   N EW YORK         ...
                                                                                                    in as the second-leading scorer and did so in his customary
D ERRICK ROSE            H 15 3      4   0   1                       33   N EW YORK         ...
                                                                                                    bench role, posting 18 points, along with nine boards, four
C OURTNEY L EE           H 11 2      3   1   1                       38   N EW YORK         ...
                                                                                                    assists, three steals and a block. Jabari Parker contributed
G IANNIS A NTETOKOUNMPO V 27 13      4   3   1                       39   M ILWAUKEE        ...
                                                                                                    15 points, four rebounds, three assists and a steal. Malcolm
G REG M ONROE            V 18 9      4   1   3                       31   M ILWAUKEE        ...
                                                                                                    Brogdon went for 12 points, eight assists and six rebounds.
JABARI PARKER            V 15 4      3   0   1                       37   M ILWAUKEE        ...
                                                                                                    Mirza Teletovic was productive in a reserve role as well,
M ALCOLM B ROGDON        V 12 6      8   0   0                       38   M ILWAUKEE        ...
                                                                                                    generating 13 points and a rebound. . . . Courtney Lee
M IRZA T ELETOVIC        V 13 1      0   0   0                       21   M ILWAUKEE        ...
                                                                                                    checked in with 11 points, three assists, two rebounds, a
J OHN H ENSON            V   2 2     0   0   0                       14   M ILWAUKEE        ...
                                                                                                    steal and a block. . . . The Bucks and Knicks face off once
...                     ... ... ... ... ... ...
                                                                                                    again in the second game of the home-and-home series, with
                                                                                                    the meeting taking place Friday night in Milwaukee.
(a) Box score: Top contingency table shows number of wins and
losses and summary of each game. Bottom table shows statistics
of each player such as points scored (P LAYER’s P TS), and total                                  (b) NBA basketball game summary: Each summary
rebounds (P LAYER’s R EB).                                                                        consists of game victory or defeat of the game and
                                                                                                  highlights of valuable players.

Table 1: Example of input and output data: task defines box score (1a) used for input and summary document of
game (1b) used as output. Extracted entities are shown in bold face. Extracted values are shown in green.

    t             199             200           201                202              203     204        205            206      207         208           209
    Yt           Jabari          Parker     contributed            15           points       ,         four        rebounds      ,         three       assists
    Zt           1                  1            0                   1               0       0           1             0         0           1            0
              JABARI              JABARI                          JABARI                              JABARI                              JABARI
    Et                                           -                                   -       -                         -         -                        -
              PARKER             PARKER                           PARKER                              PARKER                              PARKER
    At     F IRST NAME         L AST NAME        -             P LAYER P TS          -       -     P LAYER R EB        -         -     P LAYER A ST       -
    Nt           -                   -           -                   0               -       -           1             -         -           1            -

Table 2: Running example of our model’s generation process. At every time step t, model predicts each random
variable. Model firstly determines whether to refer to data records (Zt = 1) or not (Zt = 0). If random variable
Zt = 1, model selects entity Et , its attribute At and binary variables Nt if needed. For example, at t = 202, model
predicts random variable Z202 = 1 and then selects the entity JABARI PARKER and its attribute P LAYER P TS.
Given these values, model outputs token 15 from selected data record.

our training, development, test dataset are respec-                                       that have been referred to. hE NT is also used to up-
tively 2,714, 534, and 500. On average, each sum-                                         date hLM , meaning that the referred data records
mary has 384 tokens and 644 data records. Each                                            affect the text generation.
match has only one summary in our dataset, as                                                Our model decides whether to refer to x, which
far as we checked. We also collected the writer                                           data record r ∈ x to be mentioned, and how to ex-
of each document. Our dataset contains 32 differ-                                         press a number. The selected data record is used to
ent writers. The most prolific writer in our dataset                                      update hE NT . Formally, we use the four variables:
wrote 607 documents. There are also writers who
wrote less than ten documents. On average, each                                           1. Zt : binary variable that determines whether the
writer wrote 117 documents. We call our new                                                  model refers to input x at time step t (Zt = 1).
dataset ROTOW IRE -M ODIFIED.2                                                            2. Et : At each time step t, this variable indi-
                                                                                             cates the salient entity (e.g., H AWKS, L E B RON
4       Saliency-Aware Text Generation                                                       JAMES).
                                                                                          3. At : At each time step t, this variable indicates
At the core of our model is a neural language                                                the salient attribute to be mentioned (e.g., P TS).
model with a memory state hLM to generate a                                               4. Nt : If attribute At of the salient entity Et is
summary y1:T = (y1 , . . . , yT ) given a set of data                                        a numeric attribute, this variable determines if
records x. Our model has another memory state                                                a value in the data records should be output in
hE NT , which is used to remember the data records                                           Arabic numerals (e.g., 50) or in English words
                                                                                             (e.g., five).
    2
    For information about the dataset, please follow
this link:      https://github.com/aistairc/                                                To keep track of the salient entity, our model
rotowire-modified                                                                         predicts these random variables at each time step

                                                                                2104
t through its summary generation process. Run-               saliency is represented as the entity and its at-
ning example of our model is shown in Table 2                tribute being talked about. We therefore propose
and full algorithm is described in Appendix A. In            a model that refers to a data record at each time-
the following subsections, we explain how to ini-            point, and transitions to another as text goes.
tialize the model, predict these random variables,              To determine whether to transition to another
and generate a summary. Due to space limitations,            data record or not at time t, the model calculates
bias vectors are omitted.                                    the following probability:
    Before explaining our method, we describe our                        LM     E NT             LM     E NT
                                                             p(Zt = 1 | ht−1 , ht−1  ) = σ(W z (ht−1 ⊕ ht−1  )),
notation. Let E and A denote the sets of en-
                                                                                                           (3)
tities and attributes, respectively. Each record
r ∈ x consists of entity e ∈ E, attribute a ∈ A,             where σ(·) is the sigmoid function. If p(Zt = 1 |
and its value x[e, a], and is therefore represented            LM     E NT
                                                             ht−1  , ht−1  ) is high, the model transitions to an-
as r = (e, a, x[e, a]). For example, the box-                other data record.
score in Table 1 has a record r such that e =                   When the model decides to transition to another,
A NTHONY DAVIS, a = P TS, and x[e, a] = 20.                  the model then determines which entity and at-
                                                             tribute to refer to, and generates the next word
4.1   Initialization
                                                             (Section 4.3). On the other hand, if the model de-
Let r denote the embedding of data record r ∈ x.             cides not transition to another, the model generates
Let ē denote the embedding of entity e. Note that           the next word without updating the tracking states
ē depends on the set of data records, i.e., it de-          htE NT = ht−1
                                                                         E NT
                                                                              (Section 4.4).
pends on the game. We also use e for static em-
bedding of entity e, which, on the other hand, does          4.3   Selection and tracking
not depend on the game.                                      When the model refers to a new data record
   Given the embedding of entity e, attribute a,             (Zt = 1), it selects an entity and its attribute. It
and its value v, we use the concatenation layer              also tracks the saliency by putting the informa-
to combine the information from these vectors                tion about the selected entity and attribute into the
to produce the embedding of each data record                 memory vector hE NT . The model begins to select
(e, a, v), denoted as r e,a,v as follows:                    the subject entity and update the memory states if
                                                             the subject entity will change.
         r e,a,v = tanh W R (e ⊕ a ⊕ v) ,
                                          
                                                (1)             Specifically, the model first calculates the prob-
                                                             ability of selecting an entity:
where ⊕ indicates the concatenation of vectors,
                                                                              LM    E NT
and W R denotes a weight matrix.3                                p(Et = e | ht−1 , ht−1  )
  We obtain ē in the set of data records x, by sum-
                                                                  (
                                                                         E NT          LM
                                                                   exp hs W O LD ht−1
                                                                                           
                                                                                                  if e ∈ Et−1
ming all the data-record embeddings transformed                 ∝                  LM
                                                                                                              , (4)
                                                                   exp ēW N EW ht−1
                                                                                       
                                                                                                  otherwise
by a matrix:
                                          !                  where Et−1 is the set of entities that have already
                                                             been referred to by time step t, and s is defined as
                     X
                              A
        ē = tanh         W a r e,a,x[e,a] ,      (2)
                       a∈A
                                                             s = max{s : s ≤ t − 1, e = es }, which indicates
                                                             the time step when this entity was last mentioned.
where W aA is a weight matrix for attribute a.                  The model selects the most probable entity as
Since ē depends on the game as above, ē is sup-            the next salient entity and updates the set of enti-
posed to represent how entity e played in the game.          ties that appeared (Et = Et−1 ∪ {et }).
  To initialize the hidden state of each module, we             If the salient entity changes (et 6= et−1 ), the
use embeddings of  for hLM and averaged               model updates the hidden state of the tracking
embeddings of ē for hENT .                                  model hE NT with a recurrent neural network with
                                                             a gated recurrent unit (G RU; Chung et al., 2014):
4.2   Saliency transition                                               
                                                                           E NT
Generally, the saliency of text changes during text                 0
                                                                        ht−1
                                                                                                      if et = et−1
                                                               E NT            E      E NT
generation. In our work, we suppose that the                 ht       = G RU (ē, ht−1 ) else if et 6∈ Et−1
                                                                        
                                                                          G RU E (W sS hsE NT , ht−1
                                                                                                 E NT
                                                                                                      ) otherwise.
                                                                        
   3
     We also concatenate the embedding vectors that repre-
sents whether the entity is in home or away team.                                                                   (5)

                                                         2105
Note that if the selected entity at time step t, et , is               Subsequently, the hidden state of language model
identical to the previously selected entity et−1 , the                 hLM is updated:
hidden state of the tracking model is not updated.
   If the selected entity et is new (et 6∈ Et−1 ), the                              htLM = LSTM(y t ⊕ h0t , ht−1
                                                                                                             LM
                                                                                                                 ),              (11)
hidden state of the tracking model is updated with                     where y t is the embedding of the word generated
the embedding ē of entity et as input. In contrast,                   at time step t.4
if entity et has already appeared in the past (et ∈
Et−1 ) but is not identical to the previous one (et 6=                 4.5     Incorporating writer information
et−1 ), we use hsE NT (i.e., the memory state when                     We also incorporate the information about the
this entity last appeared) to fully exploit the local                  writer of the summaries into our model. Specif-
history of this entity.                                                ically, instead of using Equation (9), we concate-
   Given the updated hidden state of the tracking                                                             LM
                                                                       nate the embedding w of a writer to ht−1   ⊕ htE NT
model htE NT , we next select the attribute of the                                                  0
                                                                       to construct context vector ht :
salient entity by the following probability:
                                                                          h0t = tanh W 0H (ht−1LM
                                                                                                   ⊕ htE NT ⊕ w) , (12)
                                                                                                                
                       LM             0
   p(At = a | et , ht−1   , htE NT )               (6)
                                              0
                                                                      where W 0H is a new weight matrix. Since this new
  ∝ exp r et ,a,x[et ,a] W ATTR (ht−1
                                    LM
                                       ⊕ htE NT ) .
                                                                       context vector h0t is used for calculating the proba-
After selecting at , i.e., the most probable attribute                 bility over words in Equation (10), the writer infor-
of the salient entity, the tracking model updates the                  mation will directly affect word generation, which
memory state htE NT with the embedding of the data                     is regarded as surface realization in terms of tra-
record r et ,at ,x[et ,at ] introduced in Section 4.1:                 ditional text generation. Simultaneously, context
                                                                       vector h0t enhanced with the writer information is
                                                      0
       htE NT = G RU A (r et ,at ,x[et ,at ] , htE NT ).      (7)      used to obtain htLM , which is the hidden state of
                                                                       the language model and is further used to select the
4.4   Summary generation                                               salient entity and attribute, as mentioned in Sec-
Given two hidden states, one for language model                        tions 4.2 and 4.3. Therefore, in our model, the
  LM
ht−1   and the other for tracking model htE NT , the                   writer information affects both surface realization
model generates the next word yt . We also incor-                      and content planning.
porate a copy mechanism that copies the value of
the salient data record x[et , at ].                                   4.6     Learning objective
   If the model refers to a new data record (Zt =                      We apply fully supervised training that maximizes
1), it directly copies the value of the data record                    the following log-likelihood:
x[et , at ]. However, the values of numerical at-
tributes can be expressed in at least two different                          log p(Y1:T , Z1:T , E1:T , A1:T , N1:T | x)
manners: Arabic numerals (e.g., 14) and English                              T
                                                                             X
                                                                                                    LM     E NT
words (e.g., fourteen). We decide which one to use                      =          log p(Zt = zt | ht−1 , ht−1  )
                                                                             t=1
by the following probability:                                                 X
                                                                                                        LM     E NT
              LM
                                                                        +              log p(Et = et | ht−1 , ht−1  )
p(Nt = 1 |   ht−1 , htE NT )   = σ(W      N     LM
                                              (ht−1   ⊕   htE NT )),         t:Zt =1
                                                              (8)             X
                                                                                                             LM            0
                                                                        +              log p(At = at | et , ht−1 , htE NT )
where W N is a weight matrix. The model then                                 t:Zt =1
                                                                                       X
updates the hidden states of the language model:                        +                                              LM
                                                                                                      log p(Nt = nt | ht−1 , htE NT )
                                                                             t:Zt =1,at is num attr
       h0t = tanh W H (ht−1 LM
                                ⊕ htE NT ) ,
                                          
                                              (9)                             X
                                                                        +              log p(Yt = yt | h0t )
where W H is a weight matrix.                                                t:Zt =0
   If the salient data record is the same as the pre-
vious one (Zt = 0), it predicts the next word yt via                        4
                                                                              In our initial experiment, we observed a word repetition
a probability over words conditioned on the con-                       problem when the tracking model is not updated during gen-
text vector h0t :                                                      erating each sentence. To avoid this problem, we also update
                                                                       the tracking model with special trainable vectors v REFRESH
                                                                       to refresh these states after our model generates a period:
          p(Yt | h0t ) = softmax(W Y h0t ).                  (10)      htE NT = G RUA (v R EFRESH , htE NT )

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RG                  CS           CO
                                 Method                                               B LEU
                                             #        P%      P%     R%      F1% DLD%
                               G OLD 27.36 93.42 100. 100. 100.                       100.       100.
                          T EMPLATES 54.63 100. 31.01 58.85 40.61                     17.50      8.43
                 Wiseman et al. (2017) 22.93 60.14 24.24 31.20 27.29                  14.70     14.73
               Puduppully et al. (2019) 33.06 83.17 33.06 43.59 37.60                 16.97     13.96
                           P ROPOSED 39.05 94.43 35.77 52.05 42.40                    19.38     16.15

Table 3: Experimental result. Each metric evaluates whether important information (CS) is described accurately
(RG) and in correct order (CO).

5       Experiments                                        T EMPLATES summaries. The G OLD summary is
                                                           exactly identical with the reference summary and
5.1      Experimental settings                             each T EMPLATES summary is generated in the
We used ROTOW IRE -M ODIFIED as the dataset for            same manner as Wiseman et al. (2017).
our experiments, which we explained in Section 3.             In the latter half of our experiments, we exam-
The training, development, and test data respec-           ine the effect of adding information about writers.
tively contained 2,714, 534, and 500 games.                In addition to our model enhanced with writer in-
   Since we take a supervised training approach,           formation, we also add writer information to the
we need the annotations of the random variables            model by Puduppully et al. (2019). Their method
(i.e., Zt , Et , At , and Nt ) in the training data, as    consists of two stages corresponding to content
shown in Table 2. Instead of simple lexical match-         planning and surface realization. Therefore, by
ing with r ∈ x, which is prone to errors in the            incorporating writer information to each of the
annotation, we use the information extraction sys-         two stages, we can clearly see which part of the
tem provided by Wiseman et al. (2017). Although            model to which the writer information contributes
this system is trained on noisy rule-based annota-         to. For Puduppully et al. (2019) model, we attach
tions, we conjecture that it is more robust to errors      the writer information in the following three ways:
because it is trained to minimize the marginalized
loss function for ambiguous relations. All training        1. concatenating writer embedding w with the in-
details are described in Appendix B.                          put vector for LSTM in the content planning
                                                              decoder (stage 1);
5.2      Models to be compared                             2. concatenating writer embedding w with the in-
We compare our model5 against two baseline                    put vector for LSTM in the text generator (stage
models. One is the model used by Wiseman                      2);
et al. (2017), which generates a summary with an           3. using both 1 and 2 above.
attention-based encoder-decoder model. The other           For more details about each decoding stage, read-
baseline model is the one proposed by Puduppully           ers can refer to Puduppully et al. (2019).
et al. (2019), which first predicts the sequence of
data records and then generates a summary condi-           5.3     Evaluation metrics
tioned on the predicted sequences. Wiseman et al.
                                                           As evaluation metrics, we use BLEU score (Pap-
(2017)’s model refers to all data records every
                                                           ineni et al., 2002) and the extractive metrics pro-
timestep, while Puduppully et al. (2019)’s model
                                                           posed by Wiseman et al. (2017), i.e., relation gen-
refers to a subset of all data records, which is pre-
                                                           eration (RG), content selection (CS), and content
dicted in the first stage. Unlike these models, our
                                                           ordering (CO) as evaluation metrics. The extrac-
model uses one memory vector htE NT that tracks
                                                           tive metrics measure how well the relations ex-
the history of the data records, during generation.
                                                           tracted from the generated summary match the
We retrained the baselines on our new dataset. We
                                                           correct relations6 :
also present the performance of the G OLD and
                                                               6
                                                                The model for extracting relation tuples was trained on
    5
   Our code is available from https://github.com/          tuples made from the entity (e.g., team name, city name,
aistairc/sports-reporter                                   player name) and attribute value (e.g., “Lakers”, “92”) ex-

                                                       2107
- RG: the ratio of the correct relations out of all                                                                                                                                                   Willie Green Ronny                 Turiaf
                                                                                                                                                                                                                              Phil Pressey
                                                                                                                           Chris Kaman                               Amir Johnson       Shane Larkin                 Deyonta          Davis
                                                                                                                                                                                                                                       Furkan Aldemir
                                                                                                                                                     Nikola PekovicAlonzo       Ryan
                                                                                                                                                                          BrandanGee Shawn Hollins
                                                                                                                                                                                            WrightMarionTiago Splitter  John JaVale
                                                                                                                                                                                                                                 Salmons
  the extracted relations, where correct relations                                           Michael Carter-Williams Gary Harris
                                                                                                             Josh Smith Ed Davis Sebastian
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                                                                                                                                                                                                            Zoran
                                                                                                                                                                                                         Dekker
                                                                                                                                                                                                        Montrezl    Jr.    Devyn
                                                                                                                                                                                                                       Hezonja
                                                                                                                                                                                                                           Joe
                                                                                                                                                                                                                     Labissiere
                                                                                                                                                                                                                        Payne
                                                                                                                                                                                                                       Dragic
                                                                                                                                                                                                                       Harrell     YoungMarble
                                                                                                                                                                                                                                    Rasual
                                                                                                                                                                                                                                      Dahntay Butler
                                                                                                                                                                                                                                                 Jones
                                                                                                                                                                                                                                             James     Jones
                                                                     Chris Douglas-Roberts Kobe  Kemba
                                                                                                Paul   George Teague
                                                                                                             Walker                 Marco
                                                                                                                                   Tony
                                                                                                                                     Jeremy
                                                                                                                                          AnthonyBelinelli
                                                                                                                                             WrotenLamb     Richaun
                                                                                                                                                          Brown             Doug
                                                                                                                                                                             Holmes
                                                                                                                                                                           Tomas   Troy
                                                                                                                                                                                Leandro McDermott
                                                                                                                                                                                             Williams
                                                                                                                                                                                         Satoransky
                                                                                                                                                                                                Barbosa Fred    VanVleet
- CS: precision and recall of the relations ex-                                                 Dwight
                                                                                    Reggie Bullock
                                                                                                   Evan
                                                                                                  Blake
                                                                                                         D'Angelo
                                                                                                    Bryant Howard Rodney
                                                                                                                 Trevor
                                                                                                           Fournier
                                                                                                           Griffin
                                                                                                                        Russell   Hood
                                                                                                                              Booker
                                                                                                                           EmmanuelSerge
                                                                                                                                 FrankGlen
                                                                                                                                                     Dario
                                                                                                                                                  Beno
                                                                                                                                                  Willie
                                                                                                                                             Jabari  Damian
                                                                                                                                                 DeAndre
                                                                                                                                           Richard
                                                                                                                                            Mario
                                                                                                                                             Wesley
                                                                                                                                               Ibaka
                                                                                                                                                  Davis
                                                                                                                                            Kaminsky
                                                                                                                                                           Kevin
                                                                                                                                                        Ryan    Terrence
                                                                                                                                                                Dante
                                                                                                                                                            Udrih
                                                                                                                                                        Brown    Saric
                                                                                                                                                          Jefferson
                                                                                                                                                       Chalmers
                                                                                                                                                    Mike
                                                                                                                                                 MudiayMike
                                                                                                                                                                        Seraphin
                                                                                                                                                               Cauley-Stein
                                                                                                                                                           JJJohnsonPaul
                                                                                                                                                                     Jones
                                                                                                                                                                Redick David
                                                                                                                                                                   Liggins
                                                                                                                                                               Scott
                                                                                                                                                                    Anderson
                                                                                                                                                                  Muscala
                                                                                                                                                                            Nick
                                                                                                                                                                            Exum
                                                                                                                                                                            Dorian
                                                                                                                                                                         Larry
                                                                                                                                                                                  Jones
                                                                                                                                                                             Pierce
                                                                                                                                                                                Gerald
                                                                                                                                                                            Matthew
                                                                                                                                                                               Jordan
                                                                                                                                                                                  ZachCollison
                                                                                                                                                                                    Lee       Green
                                                                                                                                                                                             Dellavedova
                                                                                                                                                                                          Finney-Smith
                                                                                                                                                                                       Mitch McRae
                                                                                                                                                                                             LaVine
                                                                                                                                                                                    NanceTolliver
                                                                                                                                                                               Anthony           McGary
                                                                                                                                                                                                Jr. Carl Landry D.J.   Augustin
                                                                                                                                                                                                                                        Gigi Datome
                                                                                                                      Andrew Nikola         Jordan
                                                                                                                                      WigginsJokic TylerHill         Ron Johnson
                                                                                                                                                                              Baker Justin Anderson                  ZubacSheldon Mac
                                                                                                                                                       Andrew        James  Spencer
                                                                                                                                                                       Harrison   Michael        McAdooIvica
                                                                                                                                                                                             Hawes                Jordan    Adams
  tracted from the generated summary against                                                                              Devin   Jordan
                                                                                                                                       Booker
                                                                                                                                   Thaddeus    Mickey
                                                                                                                                               Jared
                                                                                                                                                   Kris   DunnJason
                                                                                                                                                         Cunningham
                                                                                                                                                       Young
                                                                                                                                                    Bismack           Biyombo   Richardson                   Joffrey
                                                                                                                                                                                                        Malcolm
                                                                                                                                                                                                           Pascal       Lauvergne
                                                                                                                                                                                                                       Delaney
                                                                                                                                                                                                                      Siakam
                                                                                                                                                                                                                          Tarik Black  Jarrod   UthoffRichardson
                                                                                                                                                                                                                                           Malachi

  those from the reference summary.
- CO: edit distance measured with normalized                      Figure 1: Illustrations of static entity embeddings e.
  Damerau-Levenshtein Distance (DLD) between                      Players with colored letters are listed in the ranking top
                                                                  100 players for the 2016-17 NBA season at https:
  the sequences of relations extracted from the
                                                                  //www.washingtonpost.com/graphics/
  generated and reference summary.                                sports/nba-top-100-players-2016/.
                                                                  Only LeBron James is in red and the other players in
6     Results and Discussions                                     top 100 are in blue. Top-ranked players have similar
                                                                  representations of e.
We first focus on the quality of tracking model and
entity representation in Sections 6.1 to 6.4, where
we use the model without writer information. We                   1901). As shown in Figure 1, which is the vi-
examine the effect of writer information in Sec-                  sualization of static entity embedding e, the top-
tion 6.5.                                                         ranked players are closely located.
                                                                     We also present the visualizations of dynamic
6.1    Saliency tracking-based model                              entity embeddings ē in Figure 2. Although we
As shown in Table 3, our model outperforms all                    did not carry out feature engineering specific to
baselines across all evaluation metrics.7 One of                  the NBA (e.g., whether a player scored double
the noticeable results is that our model achieves                 digits or not)8 for representing the dynamic en-
slightly higher RG precision than the gold sum-                   tity embedding ē, the embeddings of the players
mary. Owing to the extractive evaluation nature,                  who performed well for each game have similar
the generated summary of the precision of the rela-               representations. In addition, the change in embed-
tion generation could beat the gold summary per-                  dings of the same player was observed depending
formance. In fact, the template model achieves                    on the box-scores for each game. For instance, Le-
100% precision of the relation generations.                       Bron James recorded a double-double in a game
   The other is that only our model exceeds the                   on April 22, 2016. For this game, his embedding
template model regarding F1 score of the con-                     is located close to the embedding of Kevin Love,
tent selection and obtains the highest performance                who also scored a double-double. However, he
of content ordering. This imply that the tracking                 did not participate in the game on December 26,
model encourages to select salient input records in               2016. His embedding for this game became closer
the correct order.                                                to those of other players who also did not partici-
                                                                  pate.
6.2    Qualitative analysis of entity embedding
Our model has the entity embedding ē, which de-                  6.3                   Duplicate ratios of extracted relations
pends on the box score for each game in addition                  As Puduppully et al. (2019) pointed out, a gen-
to static entity embedding e. Now we analyze the                  erated summary may mention the same relation
difference of these two types of embeddings.                      multiple times. Such duplicated relations are not
   We present a two-dimensional visualizations of                 favorable in terms of the brevity of text.
both embeddings produced using PCA (Pearson,                         Figure 3 shows the ratios of the generated sum-
                                                                  maries with duplicate mentions of relations in the
tracted from the summaries, and the corresponding attributes
(e.g., “T EAM NAME”, “P TS”) found in the box- or line-score.     development data. While the models by Wiseman
The precision and the recall of this extraction model are re-     et al. (2017) and Puduppully et al. (2019) respec-
spectively 93.4% and 75.0% in the test data.
    7                                                                        8
      The scores of Puduppully et al. (2019)’s model signifi-          In the NBA, a player who accumulates a double-digit
cantly dropped from what they reported, especially on BLEU        score in one of five categories (points, rebounds, assists,
metric. We speculate this is mainly due to the reduced amount     steals, and blocked shots) in a game, is regarded as a good
of our training data (Section 3). That is, their model might be   player. If a player had a double in two of those five cate-
more data-hungry than other models.                               gories, it is referred to as double-double.

                                                              2108
Timofey Mozgov                                                                              JR SmithLeBron James
  4     James Jones
               Jodie  Meeks                                                   LeBron James
               Mo Williams                                                                              Beno Udrih
           DahntaySpencer
                     Jones Dinwiddie
                                                                  Kyrie Irving Kevin Love
  2             Darrun Hilliard
                                             JR Smith                                                                                                            KyrieKevin
                                                                                                                                                                       IrvingLove
                                                                   Tristan Thompson
                          Joel Anthony                                                                                          Richard Jefferson      Tristan Thompson
                                                                                                                                                                  Andre Drummond
  0                                                                                                                                 DeAndre Liggins Jon Leuer Kentavious    Caldwell-Pope
           Richard Jefferson                                                Reggie Jackson                                                      Reggie Jackson
                                                              Tobias Harris
                                                                         Kentavious Caldwell-Pope James Jones                                               Marcus Morris
                  Channing
               Steve  Blake  Frye                                       Marcus
                                                                            AndreMorris
                                                                                  Drummond                                                    Channing
                                                                                                                                           Iman        Frye
                                                                                                                                                   Tobias
                                                                                                                                                 Shumpert Harris
                   Iman   Shumpert                                                                  HenryDarrun Hilliard
                                                                                                          Ellenson
  2                                                     Matthew Dellavedova                               Michael Gbinije Jordan McRae
                                                                                                                                   Kay  Felder
                                                                                                                                   Ish Smith
                                                                                                                          Mike Dunleavy
                          Stanley Johnson                                                                     Aron Baynes
                       Aron Baynes                                                                          Stanley   Johnson
                     Anthony Tolliver
  4
            4              2             0               2              4                                  4           2         0          2          4           6
                                  April 22, 2016                                                                       December 26, 2016

Figure 2: Illustrations of dynamic entity embedding ē. Both left and right figures are for Cleveland Cavaliers vs.
Detroit Pistons, on different dates. LeBron James is in red letters. Entities with orange symbols appeared only
in the reference summary. Entities with blue symbols appeared only in the generated summary. Entities with
green symbols appeared in both the reference and the generated summary. The others are with red symbols. 2
represents player who scored in the double digits, and 3 represents player who recorded double-double. Players
with 4 did not participate in the game. ◦ represents other players.

 1.00        15.8%                                                                    1           model, which mitigates redundant references and
                                    12.7%
 0.75        20.2%                                                                    2           therefore rarely contains erroneous relations.
                                                                                      >2
 0.50                               84.2%                     95.8%                                  However, when complicated expressions such
 0.25        64.0%                                                                                as parallel structures are used our model also gen-
 0.00                                                                                             erates erroneous relations as illustrated by the un-
        Wiseman+'17            Pudupully+'19                 Proposed                             derlined sentences describing the two players who
                                                                                                  scored the same points. For example, “11-point
Figure 3: Ratios of generated summaries with dupli-
cate mention of relations. Each label represents number                                           efforts” is correct for C OURTNEY L EE but not for
of duplicated relations within each document. While                                               D ERRICK ROSE. As a future study, it is necessary
Wiseman et al. (2017)’s model exhibited 36.0% dupli-                                              to develop a method that can handle such compli-
cation and Puduppully et al. (2019)’s model exhibited                                             cated relations.
15.8%, our model exhibited only 4.2%.
                                                                                                  6.5       Use of writer information
tively showed 36.0% and 15.8% as duplicate ra-                                                    We first look at the results of an extension of
tios, our model exhibited 4.2%. This suggests that                                                Puduppully et al. (2019)’s model with writer in-
our model dramatically suppressed generation of                                                   formation w in Table 4. By adding w to con-
redundant relations. We speculate that the track-                                                 tent planning (stage 1), the method obtained im-
ing model successfully memorized which input                                                      provements in CS (37.60 to 47.25), CO (16.97
records have been selected in hsE NT .                                                            to 22.16), and BLEU score (13.96 to 18.18). By
                                                                                                  adding w to the component for surface realization
6.4     Qualitative analysis of output examples                                                   (stage 2), the method obtained an improvement in
Figure 5 shows the generated examples from val-                                                   BLEU score (13.96 to 17.81), while the effects on
idation inputs with Puduppully et al. (2019)’s                                                    the other metrics were not very significant. By
model and our model. Whereas both generations                                                     adding w to both stages, the method scored the
seem to be fluent, the summary of Puduppully                                                      highest BLEU, while the other metrics were not
et al. (2019)’s model includes erroneous relations                                                very different from those obtained by adding w
colored in orange.                                                                                to stage 1. This result suggests that writer infor-
   Specifically, the description about D ERRICK                                                   mation contributes to both content planning and
ROSE’s relations, “15 points, four assists, three                                                 surface realization when it is properly used, and
rounds and one steal in 33 minutes.”, is also used                                                improvements of content planning lead to much
for other entities (e.g., J OHN H ENSON and W ILLY                                                better performance in surface realization.
H ERNAGOMEZ). This is because Puduppully et al.                                                      Our model showed improvements in most met-
(2019)’s model has no tracking module unlike our                                                  rics and showed the best performance by incor-

                                                                                            2109
RG                         CS             CO
                 Method                                                                                         B LEU
                                                              #           P%      P%         R%        F1% DLD%
                 Puduppully et al. (2019)                 33.06       83.17     33.06      43.59      37.60        16.97        13.96
                 + w in stage 1                           28.43       84.75     45.00      49.73      47.25        22.16        18.18
                 + w in stage 2                           35.06       80.51     31.10      45.28      36.87        16.38        17.81
                 + w in stage 1 & 2                       28.00       82.27     44.37      48.71      46.44        22.41        18.90
                 P ROPOSED                                39.05 94.38 35.77 52.05 42.40                            19.38        16.15
                 +w                                       30.25 92.00 50.75 59.03 54.58                            25.75        20.84

Table 4: Effects of writer information. w indicates that W RITER embeddings are used. Numbers in bold are the
largest among the variants of each method.

                                                                            The Milwaukee Bucks defeated the New York Knicks, 105-104, at
    The Milwaukee Bucks defeated the New York Knicks, 105-                  Madison Square Garden on Saturday. The Bucks (18-16) checked in
    104, at Madison Square Garden on Wednesday evening. The                 to Saturday’s contest with a well, outscoring the Knicks (16-19) by
    Bucks (18-16) have been one of the hottest teams in the league,         a margin of 39-19 in the first quarter. However, New York by just a
    having won five of their last six games, and they have now won          25-foot lead at the end of the first quarter, the Bucks were able to pull
    six of their last eight games. The Knicks (16-19) have now              away, as they outscored the Knicks by a 59-46 margin into the second.
    won six of their last six games, as they continue to battle for the     45 points in the third quarter to seal the win for New York with the
    eighth and final playoff spot in the Eastern Conference. Giannis        rest of the starters to seal the win. The Knicks were led by Giannis
    Antetokounmpo led the way for Milwaukee, as he tallied 27               Antetokounmpo, who tallied a game-high 27 points, to go along with
    points, 13 rebounds, four assists, three blocked shots and one          13 rebounds, four assists, three blocks and a steal. The game was
    steal, in 39 minutes . Jabari Parker added 15 points, four re-          a crucial night for the Bucks’ starting five, as the duo was the most
    bounds, three assists, one steal and one block, and 6-of-8 from         effective shooters, as they posted Milwaukee to go on a pair of low
    long range. John Henson added two points, two rebounds, one             low-wise (Carmelo Anthony) and Malcolm Brogdon. Anthony added
    assist, three steals and one block. John Henson was the only            11 rebounds, seven assists and two steals to his team-high scoring total.
    other player to score in double digits for the Knicks, with 15          Jabari Parker was right behind him with 15 points, four rebounds,
    points, four assists, three rebounds and one steal, in 33 min-          three assists and a block. Greg Monroe was next with a bench-leading
    utes. The Bucks were led by Derrick Rose, who tallied 15                18 points, along with nine rebounds, four assists and three steals.
    points, four assists, three rebounds and one steal in 33 minutes.       Brogdon posted 12 points, eight assists, six rebounds and a steal.
    Willy Hernangomez started in place of Porzingis and finished            Derrick Rose and Courtney Lee were next with a pair of {11 / 11}
    with 15 points, four assists, three rebounds and one steal in 33        -point efforts. Rose also supplied four assists and three rebounds, while
    minutes. Willy Hernangomez started in place of Jose Calderon            Lee complemented his scoring with three assists, a rebound and a steal.
    ( knee ) and responded with one rebound and one block. The              John Henson and Mirza Teletovic were next with a pair of {two / two}
    Knicks were led by their starting backcourt of Carmelo An-
    thony and Carmelo Anthony, but combined for just 13 points              -point efforts. Teletovic also registered 13 points, and he added a re-
    on 5-of-16 shooting. The Bucks next head to Philadelphia to             bound and an assist. Jason Terry supplied eight points, three rebounds
    take on the Sixers on Friday night, while the Knicks remain             and a pair of steals. The Cavs remain in last place in the Eastern
    home to face the Los Angeles Clippers on Wednesday.                     Conference’s Atlantic Division. They now head home to face the
                                                                            Toronto Raptors on Saturday night.

                    (a) Puduppully et al. (2019)                                                        (b) Our model

Table 5: Example summaries generated with Puduppully et al. (2019)’s model (left) and our model (right). Names
in bold face are salient entities. Blue numbers are correct relations derived from input data records but are not
observed in reference summary. Orange numbers are incorrect relations. Green numbers are correct relations
mentioned in reference summary.

porating writer information w. As discussed in                                  generated highest quality summaries that scored
Section 4.5, w is supposed to affect both content                               20.84 points of BLEU score.
planning and surface realization. Our experimen-
tal result is consistent with the discussion.
                                                                                Acknowledgments
7   Conclusion
                                                                                We would like to thank the anonymous reviewers
In this research, we proposed a new data-to-text                                for their helpful suggestions. This paper is based
model that produces a summary text while track-                                 on results obtained from a project commissioned
ing the salient information that imitates a human-                              by the New Energy and Industrial Technology De-
writing process. As a result, our model outper-                                 velopment Organization (NEDO), JST PRESTO
formed the existing models in all evaluation mea-                               (Grant Number JPMJPR1655), and AIST-Tokyo
sures. We also explored the effects of incorpo-                                 Tech Real World Big-Data Computation Open In-
rating writer information to data-to-text models.                               novation Laboratory (RWBC-OIL).
With writer information, our model successfully

                                                                           2110
References                                                 Jiatao Gu, Zhengdong Lu, Hang Li, and Victor OK
                                                              Li. 2016. Incorporating Copying Mechanism in
Tatsuya Aoki, Akira Miyazawa, Tatsuya Ishigaki, Kei-          Sequence-to-Sequence Learning. In Proceedings of
  ichi Goshima, Kasumi Aoki, Ichiro Kobayashi, Hi-            the 54th Annual Meeting of the Association for Com-
  roya Takamura, and Yusuke Miyao. 2018. Gener-               putational Linguistics, volume 1, pages 1631–1640.
  ating Market Comments Referring to External Re-
  sources. In Proceedings of the 11th International
                                                           Caglar Gulcehre, Sungjin Ahn, Ramesh Nallapati,
  Conference on Natural Language Generation, pages
                                                             Bowen Zhou, and Yoshua Bengio. 2016. Pointing
  135–139.
                                                             the Unknown Words. In Proceedings of the 54th An-
Dzmitry Bahdanau, Kyunghyun Cho, and Yoshua Ben-             nual Meeting of the Association for Computational
  gio. 2015. Neural machine translation by jointly           Linguistics, pages 140–149.
  learning to align and translate. In Proceedings of the
  Third International Conference on Learning Repre-        Luong Hoang, Sam Wiseman, and Alexander Rush.
  sentations.                                                2018. Entity Tracking Improves Cloze-style Read-
                                                             ing Comprehension. In Proceedings of the 2018
Regina Barzilay and Mirella Lapata. 2005. Collective         Conference on Empirical Methods in Natural Lan-
  content selection for concept-to-text generation. In       guage Processing, pages 1049–1055.
  Proceedings of the conference on Human Language
  Technology and Empirical Methods in Natural Lan-         Yangfeng Ji, Chenhao Tan, Sebastian Martschat, Yejin
  guage Processing, pages 331–338.                           Choi, and Noah A Smith. 2017. Dynamic Entity
Antoine Bosselut, Omer Levy, Ari Holtzman, Corin             Representations in Neural Language Models. In
  Ennis, Dieter Fox, and Yejin Choi. 2018. Simulating        Proceedings of the 2017 Conference on Empirical
  Action Dynamics with Neural Process Networks. In           Methods in Natural Language Processing, pages
  Proceedings of the Sixth International Conference          1830–1839.
  on Learning Representations.
                                                           Chloé Kiddon, Luke Zettlemoyer, and Yejin Choi.
David L Chen and Raymond J Mooney. 2008. Learn-              2016. Globally coherent text generation with neural
  ing to sportscast: a test of grounded language ac-         checklist models. In Proceedings of the 2016 Con-
  quisition. In Proceedings of the 25th international        ference on Empirical Methods in Natural Language
  conference on Machine learning, pages 128–135.             Processing, pages 329–339.
Kyunghyun Cho, Bart van Merrienboer, Caglar Gul-           Sosuke Kobayashi, Ran Tian, Naoaki Okazaki, and
  cehre, Dzmitry Bahdanau, Fethi Bougares, Hol-              Kentaro Inui. 2016. Dynamic entity representation
  ger Schwenk, and Yoshua Bengio. 2014. Learn-               with max-pooling improves machine reading. In
  ing Phrase Representations using RNN Encoder–              Proceedings of the 15th Conference of the North
  Decoder for Statistical Machine Translation. In Pro-       American Chapter of the Association for Computa-
  ceedings of the 2014 Conference on Empirical Meth-         tional Linguistics: Human Language Technologies,
  ods in Natural Language Processing, pages 1724–            pages 850–855.
  1734.
Junyoung Chung, Caglar Gulcehre, KyungHyun Cho,            Rémi Lebret, David Grangier, and Michael Auli. 2016.
  and Yoshua Bengio. 2014. Empirical evaluation of            Neural Text Generation from Structured Data with
  gated recurrent neural networks on sequence model-          Application to the Biography Domain. In Proceed-
  ing. arXiv preprint arXiv:1412.3555.                        ings of the 2016 Conference on Empirical Methods
                                                              in Natural Language Processing, pages 1203–1213.
Elizabeth Clark, Yangfeng Ji, and Noah A Smith. 2018.
   Neural Text Generation in Stories Using Entity Rep-     Percy Liang, Michael I Jordan, and Dan Klein. 2009.
   resentations as Context. In Proceedings of the 16th       Learning semantic correspondences with less super-
   Conference of the North American Chapter of the           vision. In Proceedings of the Joint Conference of
   Association for Computational Linguistics: Human          the 47th Annual Meeting of the ACL and the 4th In-
   Language Technologies, pages 2250–2260.                   ternational Joint Conference on Natural Language
                                                             Processing of the AFNLP, pages 91–99.
Xavier Glorot and Yoshua Bengio. 2010. Understand-
  ing the difficulty of training deep feedforward neu-
  ral networks. In Proceedings of the thirteenth in-       Tianyu Liu, Kexiang Wang, Lei Sha, Baobao Chang,
  ternational conference on artificial intelligence and       and Zhifang Sui. 2018. Table-to-text Generation by
  statistics, pages 249–256.                                  Structure-aware Seq2seq Learning. In Proceedings
                                                              of the Thirty-Second AAAI Conference on Artificial
Alex Graves, Greg Wayne, Malcolm Reynolds,                    Intelligence.
  Tim Harley, Ivo Danihelka, Agnieszka Grabska-
  Barwińska, Sergio Gómez Colmenarejo, Edward            Thang Luong, Hieu Pham, and Christopher D Man-
  Grefenstette, Tiago Ramalho, John Agapiou, et al.          ning. 2015. Effective Approaches to Attention-
  2016.    Hybrid computing using a neural net-              based Neural Machine Translation. In Proceedings
  work with dynamic external memory. Nature,                 of the 2015 Conference on Empirical Methods in
  538(7626):471.                                             Natural Language Processing, pages 1412–1421.

                                                       2111
Hongyuan Mei, Mohit Bansal, and Matthew R Walter.           Yasufumi Taniguchi, Yukun Feng, Hiroya Takamura,
  2016. What to talk about and how? Selective Gener-          and Manabu Okumura. 2019. Generating Live
  ation using LSTMs with Coarse-to-Fine Alignment.            Soccer-Match Commentary from Play Data. In Pro-
  In Proceedings of the 15th Conference of the North          ceedings of the Thirty-Third AAAI Conference on
  American Chapter of the Association for Computa-            Artificial Intelligence.
  tional Linguistics: Human Language Technologies,
  pages 720–730.                                            Zhaopeng Tu, Yang Liu, Zhengdong Lu, Xiaohua Liu,
                                                              and Hang Li. 2017. Context gates for neural ma-
Soichiro Murakami, Akihiko Watanabe, Akira                    chine translation. Transactions of the Association
  Miyazawa, Keiichi Goshima, Toshihiko Yanase, Hi-            for Computational Linguistics, 5:87–99.
  roya Takamura, and Yusuke Miyao. 2017. Learning
  to generate market comments from stock prices.            Jason Weston, Sumit Chopra, and Antoine Bordes.
  In Proceedings of the 55th Annual Meeting of the             2015. Memory Networks. In Proceedings of the
  Association for Computational Linguistics, pages             Third International Conference on Learning Repre-
  1374–1384.                                                   sentations.
Graham Neubig, Chris Dyer, Yoav Goldberg, Austin            Sam Wiseman, Stuart Shieber, and Alexander Rush.
  Matthews, Waleed Ammar, Antonios Anastasopou-               2017. Challenges in Data-to-Document Generation.
  los, Miguel Ballesteros, David Chiang, Daniel               In Proceedings of the 2017 Conference on Empiri-
  Clothiaux, Trevor Cohn, et al. 2017. Dynet: The             cal Methods in Natural Language Processing, pages
  dynamic neural network toolkit. arXiv preprint              2253–2263.
  arXiv:1701.03980.
                                                            Zichao Yang, Phil Blunsom, Chris Dyer, and Wang
Kishore Papineni, Salim Roukos, Todd Ward, and Wei-           Ling. 2017. Reference-Aware Language Models.
  Jing Zhu. 2002. BLEU: a method for automatic                In Proceedings of the 2017 Conference on Empiri-
  evaluation of machine translation. In Proceedings           cal Methods in Natural Language Processing, pages
  of the 40th annual meeting on association for com-          1850–1859.
  putational linguistics, pages 311–318.
Karl Pearson. 1901. On lines and planes of closest fit to   A   Algorithm
  systems of points in space. The London, Edinburgh,
  and Dublin Philosophical Magazine and Journal of          The generation process of our model is shown
  Science, 2(11):559–572.                                   in Algorithm 1. For a concise description, we
                                                            omit the condition for each probability notation.
Ratish Puduppully, Li Dong, and Mirella Lapata. 2019.
  Data-to-Text Generation with Content Selection and         and  represent “start of the doc-
  Planning. In Proceedings of the Thirty-Third AAAI         ument” and “end of the document”, respectively.
  Conference on Artificial Intelligence.
Sashank J Reddi, Satyen Kale, and Sanjiv Kumar.
  2018. On the convergence of adam and beyond. In           B   Experimental settings
  Proceedings of the Sixth International Conference
                                                            We set the dimensions of the embeddings to 128,
  on Learning Representations.
                                                            and those of the hidden state of RNN to 512 and all
Lei Sha, Lili Mou, Tianyu Liu, Pascal Poupart, Sujian       of parameters are initialized with the Xavier ini-
  Li, Baobao Chang, and Zhifang Sui. 2018. Order-
  planning neural text generation from structured data.
                                                            tialization (Glorot and Bengio, 2010). We set the
  In Proceedings of the Thirty-Second AAAI Confer-          maximum number of epochs to 30, and choose the
  ence on Artificial Intelligence.                          model with the highest B LEU score on the devel-
Sainbayar Sukhbaatar, Jason Weston, Rob Fergus, et al.
                                                            opment data. The initial learning rate is 2e-3 and
  2015. End-to-end memory networks. In Advances             AMSGrad is also used for automatically adjusting
  in neural information processing systems, pages           the learning rate (Reddi et al., 2018). Our imple-
  2440–2448.                                                mentation uses DyNet (Neubig et al., 2017).
Ilya Sutskever, Oriol Vinyals, and Quoc V Le. 2014.
   Sequence to sequence learning with neural net-
   works. In Advances in neural information process-
   ing systems, pages 3104–3112.
Kumiko Tanaka-Ishii, Kôiti Hasida, and Itsuki Noda.
  1998. Reactive content selection in the generation
  of real-time soccer commentary. In Proceedings of
  the 36th Annual Meeting of the Association for Com-
  putational Linguistics and 17th International Con-
  ference on Computational Linguistics, pages 1282–
  1288.

                                                        2112
Algorithm 1: Generation process
    Input: Data records s,
    Annotations Z1:T , E1:T , A1:T , N1:T
                                            LM        E NT
 1 Initialize {r e,a,v }r∈x , {ē}e∈E , h0 , h0
 2 t ← 0
 3 et , yt ← N ONE , < S O D >
 4 while yt 6=< E O D > do
 5       t←t+1
 6       if p(Zt = 1) ≥ 0.5 then
             /* Select the entity                                           */
 7           et ← arg max p(Et = e0t )
 8           if et 6∈ Et−1 then
                   /* If et is a new entity                                 */
                     E NT0          E        E NT
 9                 ht       ← G RU (ēt , ht−1 )
10                 Et ← Et−1 ∪ {et }
11           else if et 6= et−1 then
                   /* If et has been observed before, but is different from
                         the previous one.                                  */
                     E NT ’         E     S E NT         E NT
12                 ht       ← G RU (W hs , ht−1 ),
13                 where s = max{s : s ≤ t − 1, e = es }
14           else
15                 htE NT ’ ← ht−1
                                E NT

             /* Select an attribute for the entity, et .                    */
16           at ← arg max p(At = at )      0
                                                           0
17           htE NT ← G RU A (r et ,at ,x[et ,at ] , htE NT )
18           if at is a number attribute then
19                 if p(Nt = 1) ≥ 0.5 then
20                      yt ← numeral of x[et , at ]
21                 else
22                      yt ← x[et , at ]
23                 end
24           else
25                 yt ← x[et , at ]
               0
             ht ← tanh W H (ht−1      LM
                                          ⊕ htE NT )
                                                         
26

27           htLM ← L STM(y t ⊕ h0t , ht−1    LM
                                                    )
28       else
29           et , at , htE NT ← et−1 , at−1 , ht−1
                                                 E NT
               0                 H
             ht ← tanh W (ht−1 ⊕ htE NT )
                                      LM
                                                         
30
31           yt ← arg max p(Yt )
32           htLM ← L STM(y t ⊕ h0t , ht−1    LM
                                                    )
33       end
34       if yt is “.” then
35           htE NT ← G RU A (v R EFRESH , htE NT )
36 end
37 return y1:t−1 ;

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