Interview with Greta Panova - Toufik Mansour - Enumerative Combinatorics and ...

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Interview with Greta Panova - Toufik Mansour - Enumerative Combinatorics and ...
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                                    Enumerative Combinatorics and Applications       ECA 2:1 (2022) Interview #S3I3
                                                                                     https://doi.org/10.54550/ECA2022V2S1I3

                                           Interview with Greta Panova
                                                                                                  Toufik Mansour

                                 Greta Panova completed her undergraduate studies at the Mas-
                                 sachusetts Institute of Technology, where she obtained two
                                 bachelor’s degrees: in Mathematics and in Electrical Science
                                 and Engineering. She completed her master’s studies at the
                                 University of California, Berkeley. She obtained a Ph.D. from
                                 Harvard University in 2011, under the direction of Richard
                                 Stanley. She currently holds the position of Associate Pro-
                                 fessor (with tenure) at the University of Southern California.
                                 From 2011 up to 2014 she was a Simons Postdoctoral Fellow
                                 at the University of California Los Angeles. During the period
                                 2014-2018, she was an Assistant Professor, promoted to Asso-
ciate (with tenure), at the University of Pennsylvania. During the period 2017-2018, she was
a Von Neumann Fellow at the Institute for Advanced Studies in Princeton. Professor Panova
has given numerous talks at many conferences and seminars. We list here some of her ple-
nary talks: Triangle Lectures in Combinatorics, Greensboro, NC. (2016); Formal Power Series
and Algebraic Combinatorics, London, UK (2017); Algebraic and Enumerative Combinatorics
Conference, Okayama, Japan (2018). Greta Panova received many prizes and awards with the
most recent one, the IMI prize for 2020, the prize awarded by the Institute of Mathematics and
Informatics of the Bulgarian Academy of Sciences. She is currently one of the Editors-in-chief
of The Electronic Journal of Combinatorics.

Mansour: Professor Panova, first of all, we                           and the problems solved with external tools,
would like to thank you for accepting this in-                        all of which make this area very diverse, well-
terview. Would you tell us broadly what com-                          connected to others, and its boundaries hard
binatorics is?                                                        to define.
Panova: Thank you for inviting me, it is an Mansour: What do you think about the de-
honor to be interviewed.                    velopment of the relations between combina-
  Combinatorics is generally speaking the torics and the rest of mathematics?
area of mathematics that studies discrete ob-                         Panova: Combinatorics is centrally posi-
jects without too much underlying structure                           tioned within mathematics. Combinatorial ob-
and relations, which is what distinguishes it                         jects, in their simple structure, could manifest
from algebra and number theory. Combina-                              in external problems and then combinatorial
torics itself has many subareas which do not                          methods become powerful tools. For exam-
necessarily interact much with each other –                           ple, at the heart of algebraic combinatorics lie
graph theory, enumerative, analytic, algebraic                        enumerative techniques and symmetric func-
combinatorics can all be very different and                           tions, which directly apply in representation
even within themselves divided. Combina-                              theory to understand module dimensions and
torics has both its methods and its problems,                         structure through multiplicities. We can see
the methods could be applied to other fields,                         such connections everywhere – in probability
    The authors: Released under the CC BY-ND license (International 4.0), Published: April 2, 2021
    Toufik Mansour is a professor of mathematics at the University of Haifa, Israel. His email address is tmansour@univ.haifa.ac.il
Interview with Greta Panova

and statistical mechanics, algebra and number                    combinatorial quantities through the prism of
theory, algebraic geometry, topology... Com-                     complexity classes and explain formally why
binatorics goes beyond math, as it is among                      we do not have “nice” formulas, or even “com-
the main tools in theoretical computer science,                  binatorial interpretations” sometimes.
game theory, etc. Moreover, the interaction is                   Mansour: We would like to ask you about
two-way, as algebraic and probabilistic meth-                    your formative years. What were your early
ods play an important role and seemingly sim-                    experiences with mathematics? Did that hap-
ple combinatorial problems have been solved                      pen under the influence of your family or some
with the powerful machinery of other fields.                     other people?
For example, algebraic geometry has been used
                                                                 Panova: My parents are both very far from
to prove the unimodality of combinatorial se-
                                                                 mathematics, although as a law professor (my
quences as in the works of Richard Stanley1
                                                                 mother) and as a medical doctor (my father),
in the 80s and June Huh2 much more recently;
                                                                 education in my family has always been highly
Haiman’s3 proof of the n! conjecture is another
                                                                 valued. My mother was steering me to study
example.
                                                                 languages early on, which I greatly resisted,
Mansour: What have been some of the main                         and instead spent my time at home quietly
goals of your research?                                          drawing and disassembling things out of cu-
Panova: I try to find connections with other                     riosity and desire to build something else out
fields, expand the application of combinato-                     of their parts resulting in inevitable destruc-
rial methods there and also solve combinato-                     tion and sometimes injury. My memories from
rial problems using external methods. One                        elementary school are quite blank in the cloud
direction is the study of interacting particle                   of my peer’s hostility. When I was in 4th grade
systems, dimer models in statistical mechanics                   my mother won a Humboldt fellowship and we
which often benefit from the use of symmetric                    spent one year in Germany, where I started
functions; and in the opposite direction proba-                  exhibiting some math skills recognized by the
bilistic methods can explain the asymptotics of                  teachers. Back in Bulgaria, I went to a better
combinatorial quantities. Another direction is                   middle school, and after 7th grade I was ad-
computational complexity in theoretical com-                     mitted to and enrolled in the National High-
puter science, where a good understanding of                     School of Mathematics and Sciences, defeating
structure constants in algebraic combinatorics                   my mother’s push to go to a language high-
(e.g. the Kronecker and plethysm coefficients)                   school by failing the literature entrance exam.
could lead to computational lower bounds.                        In high school, I started going to math compe-
This is the basis of geometric complexity the-                   titions, which turned out to be actually fun. I
ory (GCT) which aims to distinguish the al-                      ultimately made it to the national team for the
gebraic version of P vs NP, the VP vs VNP                        IMO, where I got gold and two silver medals.
problem, by exploiting the symmetries of the                     These were my entrance ticket to MIT and the
universal polynomials – the permanent and de-                    rest is in my CV. I must add though, that de-
terminant. Unfortunately, our work on Kro-                       spite all the math I was doing in high school,
necker and plethysm coefficients and disprove                    during my entire childhood I wanted to become
of the weak GCT conjecture revealed that the                     an architect and that is what I started with at
stepping stones in GCT are higher than we                        MIT.
can currently reach4,5 . The connections be-
tween algebraic combinatorics and computa-                       Mansour: Were there specific problems that
tional complexity extend further beyond these                    made you first interested in combinatorics?
applications, and another goal is to understand                  Panova: No specific problem, but rather the
  1 R.  P. Stanley, Log-concave and unimodal sequences in algebra, combinatorics, and geometry, In Graph theory and its applica-
tions: East and West (Jinan, 1986), volume 576 of Ann. New York Acad. Sci., pages 500–535. New York Acad. Sci., New York,
1989.
   2 J. Huh, Milnor numbers of projective hypersurfaces and the chromatic polynomial of graphs, J. Amer. Math. Soc. 25:3 (2012),

907–927.
   3 M. Haiman, Hilberts schemes, polygraphs, and the Macdonald positivity conjecture, J. Amer. Math. Soc. 14:4 (2001), 941–1006.
   4 C. Ikenmeyer and G. Panova, Rectangular Kronecker coefficients and plethysms in geometric complexity theory, Adv. Math.

319, (2017), 40–66.
   5 P. Bürgisser, C. Ikenmeyer, and G. Panova, No occurrence obstructions in geometric complexity theory, J. Amer. Math. Soc.

32 (2019), 163–193.

ECA 2:1 (2022) Interview #S3I3                                                                                                 2
Interview with Greta Panova

problem style as a whole. I liked its problem-                      Mansour: What would guide you in your re-
solving nature and the fact that I could start                      search? A general theoretical question or a
working on a problem without much back-                             specific problem?
ground knowledge.                                                   Panova: Usually both. I had to start with
Mansour: What was the reason you chose                              some area I want to understand or find con-
Harvard University for your Ph.D. and your                          nections to and then look for specific problems
advisor Richard Stanley?                                            there to help me explore further. Often other
Panova: Initially my intentions were to do                          researchers would approach me with more con-
algebraic number theory and went to Har-                            crete problems, which is usually a very enlight-
vard as one of the best places for that. Af-                        ening opportunity to learn about a new sub-
ter gaining more exposure across math fields, I                     area and find more connections. I am a prob-
carefully reexamined my interests and what I                        lem solver, and ultimately it is the concrete
liked about math and decided to do combina-                         problems that keep me awake at night.
torics. I knew Richard Stanley from the fresh-                      Mansour: When you are working on a prob-
man problem-solving seminar at MIT and it all                       lem, do you feel that something is true even
seemed like a natural choice.                                       before you have the proof?
Mansour: What was the problem you worked                            Panova: Usually yes, but I could be dialectic.
on in your thesis?                                                  I would try to prove and disprove at the same
Panova: There were several little problems I                        time until it is clear which way it goes.
solved during my Ph.D. and some went into                           Mansour: What three results do you consider
my thesis6,7,8 . They were all some form of                         the most influential in combinatorics during
enumeration of permutations or tableaux using                       the last thirty years?
tools from algebraic combinatorics like sym-                        Panova: Answering the question literally, in-
metric functions, RSK, etc. The main prob-                          fluential would be the results which lead to
lem was the enumeration of standard Young                           a lot of subsequent work, and as such per-
tableaux of certain truncated shapes, the ones                      haps not specific Theorems, but rather con-
obtained by removing a partition from the up-                       jectures or newly defined objects would top
per right corner of a Young diagram (in English                     the list. Specifically, these would be (in no
notation). Such objects had not been studied                        particular order): the discovery of cluster al-
before. Ron Adin and Yuval Roichman had                             gebras by Fomin and Zelevinsky11 ; the study
noticed experimentally that for certain shapes                      of dimer models starting with the work on
the number of SYTs (linear extensions) seems                        the Aztec diamond initiated by Cohn–Elkies–
to have product formulas since they did not                         Kuperberg–Larsen-Propp12 and greatly ex-
have large prime factors9 . They had asked                          panded by Kenyon–Okounkov–Sheffield13 and
Richard Stanley about this phenomenon and                           evolved in the area of integrable probability
he passed it on to me to solve. In order to solve                   driven by A. Borodin, I. Corwin, and many
it, I used symmetric functions, complex anal-                       other famous mathematicians14 . The study of
ysis, volumes of polytopes, etc, and figuring                       diagonal harmonics with the flagship results –
all these techniques out was quite enlightening                     the n! conjecture, proven by Haiman, and the
to me and got me interested in their natural                        subsequent “Shuffle conjecture” of Haglund–
continuation within integrable probability10 .                      Haiman–Loehr–Remmel–Ulyanov15 , more re-
   6 G. Panova, Bijective enumeration of permutations starting with a longest increasing subsequence, Discrete Math. Theor.

Comp. Sci. Proc. (2010), 973–982
   7 A. Crites, G. Panova, and G. Warrington, Separable permutations and Greene’s theorem (2010), Ars Combin. 128 (2016),

103–116
   8 G. Panova, Tableaux and plane partitions of truncated shapes (2010), Adv. in Appl. Math. 49:3-5 (2012), 196–217.
   9 Subsequently they independently solved and published this: R. Adin, R. King, Y. Roichman, Enumeration of standard Young

tableaux of certain truncated shapes, The Electronic J. Combin. 18(2) (2011), #P20.
  10 Integrable probability is the area at the intersection of statistical mechanics and probability which studies integrable particle

models, see e.g. https://en.wikipedia.org/wiki/Integrable_system.
  11 S. Fomin and A. Zelevinsky, Cluster algebras I: Foundations, J. Amer. Math. Soc. 15 (2002), 497–529.
  12 N. Elkies, G. Kuperberg, M. Larsen, and J. Propp, Alternating-sign matrices and domino tilings, J. Algebraic Combin.

1:111–132 (1992) 219–234.
  13 R. Kenyon, A., Okounkov, and S. Sheffield, Dimers and amoebae, Ann. of Math. (2) 163 (2006), 1019–1056.
  14 See https://www.claymath.org/events/cmi-himr-integrable-probability-summer-school.
  15 J. Haglund, M. Haiman, N. Loehr, J. B. Remmel, and A. Ulyanov, A combinatorial formula for the character of the diagonal

coinvariants, Duke Math. J. 126 (2005), 195–232.

ECA 2:1 (2022) Interview #S3I3                                                                                                      3
Interview with Greta Panova

cently proven by Carlsson-Mellit16 , and all                    tinguish the core.
the work in symmetric functions these conjec-                   Mansour: What do you think about the dis-
tures/results have motivated over the past 30                   tinction between pure and applied mathemat-
years. This is only within algebraic combi-                     ics that some people focus on? Is it mean-
natorics, as of course, there have been major                   ingful at all in your case? How do you see the
breakthrough results in other areas of combi-                   relationship between so-called “pure” and “ap-
natorics.                                                       plied” mathematics?
Mansour: What are the top three open ques-                      Panova: As long as theorems are being proven
tions in your list?                                             and mathematics is being developed, it could
Panova: There is one major open problem                         be considered “pure”. I would consider “ap-
– distinguishing the VP from VNP in arith-                      plied” that part of math that usually falls
metic complexity theory17 , which seems more                    into modeling and engineering and solves their
accessible than P vs NP18 . Specifically in alge-               problems rather than proving new math theo-
braic combinatorics: the “combinatorial inter-                  rems. Most of the mathematics we do and pub-
pretation” of Kronecker coefficients and all the                lish in journals like ECA qualifies as “pure” by
other “mysteriously” nonnegative coefficients                   that measure, and further division is meaning-
and structure constants. Such interpretations                   less.
may probably not exist, following Igor Pak’s                    Mansour: What advice would you give to
idea that Kronecker coefficients could be prov-                 young people thinking about pursuing a re-
ably not in #P (under some reasonable com-                      search career in mathematics?
putational hypothesis).                                         Panova: Do mathematics for its beauty and
Mansour: What kind of mathematics would                         the fun of the Eureka moment when you solve a
you like to see in the next ten-to-twenty years                 problem. Do not be afraid of the long academic
as the continuation of your work?                               path because at every step there are multiple
Panova: I would like to see further devel-                      opportunities – math is used in so many areas
opment in the connections between algebraic                     in the industry besides academia, it is worth
combinatorics and computer science and prob-                    the journey.
ability. I hope to see progress towards the ques-               Mansour: Would you tell us about your in-
tions listed above.                                             terests besides mathematics?
Mansour: Do you think that there are core or                    Panova: I have an interest in molecular bi-
mainstream areas in mathematics? Are some                       ology and do some collaborations helping to
topics more important than others?                              model molecular dynamics in the DNA repair
Panova: Yes. Most of the perceptions of                         processes. While this is still “research work”,
“core” and “important” stem from the opin-                      it is unrelated to my main mathematical re-
ions of the experts and are often function on                   search career.
the number of researchers working in a given                        On a more personal level, I really like ex-
area. Yet there are many subareas with a lot                    ploring nature. I go hiking, mountaineering,
of activity due largely to the variety and ac-                  and I like to capture the beauty of nature with
cessibility of the questions. I would measure                   photographs. I used to paint and draw, but I
the importance of an area by its connectivity                   have not pursued this much recently.
to other areas of mathematics or other sciences                 Mansour: In a series of four papers, co-
and define its influences via the power and ap-                 authored with Morales and Pak19,20,21,22 , on
plicability of its methods. Then we would dis-                  Hook formulas for skew shapes, you obtained
 16 E. Carlsson and A. Mellit, A proof of the shuffle conjecture, J. Amer. Math. Soc. 31 (2018), 661–697.
 17 For example, see A. Shpilka and A. Yehudayoff, Arithmetic Circuits: A Survey of Recent Results and Open Questions, Foun-
dations and Trends in Theoretical Computer Science 5:3–4 (2010), 207–388.
 18 For                             ?
         example, see S. Aaronson, P = N P , in Open problems in mathematics, Springer, Cham, 2016, 1–122
 19 A.  H. Morales, I. Pak, and G. Panova, Hook formulas for skew shapes I. q-analogues and bijections, J. Combin. Theory, Ser.
A 154 (2018), 350–405.
  20 A. H. Morales, I. Pak, and G. Panova, Hook formulas for skew shapes II. Combinatorial proofs and enumerative applications,

SIAM J. Discrete Math. 31 (2017), 1953–1989.
  21 A. H. Morales, I. Pak, and G. Panova, Hook formulas for skew shapes III. Multivariate and product formulas, Algebraic

Combinatorics 2:5 (2019), 815–861.
  22 A. H. Morales, I. Pak, and G. Panova, Asymptotics for the number of standard Young tableaux of skew shape, European J.

Combin. 70 (2018), 26–49.

ECA 2:1 (2022) Interview #S3I3                                                                                               4
Interview with Greta Panova

interesting and important results regarding the                   from Representation theory, are used to de-
Naruse hook-length formula23 which has al-                        scribe the decomposition of the tensor product
ready motivated a great deal of recent interest                   of two irreducible representations of a symmet-
in the enumeration of skew tableaux and re-                       ric group into irreducible representations. How
lated topics. Would you tell us about this for-                   do they come into play in combinatorics in gen-
mula, the main motivation behind this project,                    eral and in your research in particular?
and some potential applications of techniques                     Panova: Ever since their introduction by
developed in these papers? Will this series con-                  Murnaghan25 more than 80 years ago, they
tinue with new surprising results and applica-                    have posed a major problem – to give any kind
tions?                                                            of positive combinatorial formula for them.
Panova: One of the most fascinating classical                     Kronecker coefficients can be expressed using
results in algebraic combinatorics is the Hook-                   characters of Sn , Schur functions, and even
length formula of Frame–Robinson–Thrall24                         contingency arrays. Yet, their inherent non-
for the number f λ of Standard Young Tableaux                     negativity (as multiplicities of irreducible rep-
of a given shape λ, equivalently the dimen-                       resentations) and their semigroup property are
sion of the irreducible Sn representation of                      completely mysterious from all these (nonpos-
the Specht module of λ, which gives f λ as n!                     itive) combinatorial formulas. Ever since we
divided by the product of hooks of λ. For                         started looking at them with Igor Pak, I have
SYTs of skew shapes no such formula exists,                       been trying to understand them and answer
as can be seen from the special case of f δn /δn−2                this question, perhaps in the negative formally
given by the Euler numbers. In 2014 Hi-                           using computational complexity notions. The
roshi Naruse presented a remarkable formula                       various formulas have given us a lot of partial
expressing f λ/µ as n! times a sum over “ex-                      results, and also implications to other prob-
cited” diagrams of µ inside λ weighted by                         lems (like Sylvester’s26 unimodality for the
the inverse product of hook lengths of each                       number of integer partitions inside a rectangle,
diagram. Naturally, such a beautiful result                       ref. our papers with Igor Pak). A major moti-
needed a “combinatorial” explanation and we                       vation to study them came from GCT, where
set on to [re]prove it by first generalizing it to                they can be used to understand the represen-
q-weighted enumeration over skew SSYTs and                        tation theory of the coordinate rings for the
reverse plane partitions and proving those re-                    determinant and permanent and thus hope-
sults algebraically, bijectively, and later on via                fully distinguish them and possibly prove that
recursions and non-intersecting lattice paths.                    V P 6= V N P . In the course of our investiga-
Thanks to the positive-sum and nice weights                       tions, we disproved a cornerstone conjecture
the formula proved to be useful for applica-                      in GCT5 , but we also understood more about
tions, mostly related to asymptotic results (for                  them.
the number of skew SYTs to lozenge tilings and                    Mansour: In the paper entitled Asymptotics
more refined asymptotics and probabilistic be-                    of symmetric polynomials with applications to
havior of SYTs). I am expecting to see more                       statistical mechanics and representation the-
such asymptotic applications of this formula                      ory, co-authored by Gorin27 , you developed
and I am hoping for further connections to                        a new method for studying the asymptotics
Schur functions. The new, though not entirely                     of symmetric polynomials of representation-
surprising, results concern its deformations, for                 theoretic origin as the number of variables
example to Grothendieck polynomials and the                       tends to infinity. Would you explain this
associated standard increasing tableaux.                          method and some of its applications briefly?
Mansour: Kronecker coefficients, as ’tools’                       Models from statistical physics have always
  23 H. Naruse, Schubert calculus and hook formula, talk slides at 73rd Sém. Lothar. Combin., Strobl, Austria, 2014; available at

tinyurl.com/z6paqzu.
  24 J. S. Frame, G. de B. Robinson, and R. M. Thrall, The hook graphs of the symmetric group, Canad. J. Math. 6 (1954),

316–324.
  25 D. Murnaghan, The analysis of the direct product of irreducible representations of the symmetric groups, Amer. J. Math. 60:9

(1938), 44–65.
  26 J. J. Sylvester, Proof of the hitherto undemonstrated fundamental theorem of invariants, Philos. Mag. 5 (1878), 178–188,

reprinted in: Coll. Math. Papers, vol. 3, Chelsea, New York, 1973, 117–126.
  27 V. Gorin and G. Panova, Asymptotics of symmetric polynomials with applications to statistical mechanics and representation

theory, Ann. Probab. 43:6 (2015), 3052–3132.

ECA 2:1 (2022) Interview #S3I3                                                                                                  5
Interview with Greta Panova

been a rich source of interesting problems for                netics and reaction kinetics. Subsequently, the
combinatorics and probability. Are there spe-                 fields of systems biology and computational
cific problems in this direction in your research             biology (genetics and neuroscience) emerged,
plan for the near future?                                     but their level of abstraction and generality is
Panova: Indeed, as I have mentioned above,                    nowhere close to what we have seen in theoreti-
integrable probability uses symmetric func-                   cal physics. The main issue comes from the in-
tion theory. The normalized Schur functions                   herent complexity of living systems and life’s
can be interpreted as a variant of the mo-                    uniqueness. Despite the great variety of liv-
ment generating functions for observables in                  ing organisms, the underlying biology is all too
the lozenge tiling model (e.g. positions of hor-              similar in its building blocks and basic mech-
izontal lozenges near the boundary). Their                    anism and at the same, these are too complex
asymptotic behavior gives us the probability                  to pick apart.
distributions of certain lozenges and can be                  Mansour: You have extensive experience with
further used to derive limit surfaces and be-                 major mathematics competitions such as In-
havior of such dimer models. These meth-                      ternational Mathematics Olympiads and Put-
ods, however, rely strongly on the geometry                   nam. Do you think that mathematics com-
of the domain/boundary conditions and dimer                   petitions play a crucial role to inspire young
weights, and extending our understanding fur-                 students for a research career?
ther is still ongoing. Some specific problems                 Panova: Mathematical competitions defi-
concern the asymptotics of normalized skew                    nitely help popularize mathematics among stu-
Schur functions or the study of tiling models                 dents and also help them develop problem-
with long-range interaction which we encoun-                  solving skills, which are useful also outside aca-
tered when studying the seemingly unrelated                   demic math like tech and finance jobs. The
problem on maximal Schubert polynomials.                      caveat is that this very inspiring (and fun!)
Mansour: Combinatorics is full of important                   experience could also be slightly misleading
formulas. Which three are your favorite?                      since, unlike competitions, research problems
Panova: The original hook-length formula                      are rarely solvable in 3 hours.
for the number of SYTs23 has been a major                     Mansour: In your work, you have extensively
source of inspiration and beautiful results. The              used combinatorial reasoning to address im-
Lindström28 , Gessel–Viennot29 , and Karlin–                 portant problems. How do enumerative tech-
MacGregor30 determinantal formula for count-                  niques engage in your research?
ing non-intersecting lattice paths has been use-              Panova: Enumerative techniques help from
ful across the areas from algebra to probabil-                the beginning by breaking the problem into
ity. The matrix-tree theorem and Weyl deter-                  possibly smaller structures, making simpler
minantal formula are also up on the list.                     models, finding symmetries and recursions.
Mansour: You were one of the panelists at                     Generating functions are also a very powerful
the workshop, “Towards a new theoretical bi-                  tool by itself.
ology,” in 2018 at the University of Pennsylva-               Mansour: It is a fact that not many women
nia. Would you tell us about the main differ-                 follow a professional career in mathematics. It
ences between the new and the old? How does                   is a discussion around the globe on how to get
combinatorics involve there?                                  more women into mathematics. What do you
Panova: I believe I was on this panel be-                     think about this issue? What should be done
cause I am a mathematician with some work                     in the next ten years to involve more women
in molecular biology, but it is unrelated to my               in mathematics?
work in combinatorics. The discussion in this                 Panova: Algebraic combinatorics is doing
workshop was focused on why biology has not                   something right, as it seems that the propor-
been able to take such advantage of mathe-                    tions of women in this field are higher than
matical methods and developed as theoretical                  in most other areas of math. A lot of the
physics has. The “old” theoretical biology re-                current efforts focus on recruitment at later
volved mostly around models in population ge-                 stages, but I think the issues start already in
 28 B. Lindström, On the vector representation of induced matroids, Bull. London Moth. Sot. 5 (1973), 85–90.
 29 I.Gessel and G. Viennot, Binomial determinants, paths, and Hook length formulae, Adv. Math.58 (1985), 300–321.
 30 S. Karlin and J. G. McGregor, Coincidence probabilities, Pacific J. Math. 9 (1959), 1141–1164.

ECA 2:1 (2022) Interview #S3I3                                                                                       6
Interview with Greta Panova

middle school. There are too many stereotypes                   thought process for the proof of one of your
poisoning the experience from early on – from                   favorite results? How did you become inter-
gender biases to the unpopularity of math as a                  ested in that problem? How long did it take
subject (especially in the US). We should each                  you to figure out the proof? Did you have a
do our part in debunking these stereotypes at                   “eureka moment”?
every level.                                                    Panova: I must say that the older and more
Mansour: You are the recipient of the IMI                       experienced I get, the less surprise and excite-
Prize for the year 2020, a prize awarded by                     ment of the “eureka moment” I have. Recently
the Institute of Mathematics and Informatics                    my solutions have been gradually built up from
of the Bulgarian Academy of Sciences. The                       smaller problems and often result from finding
prize will be presented during the International                connections. My favorite results are “Rectan-
Conference “Mathematics Days of in Sofia” in                    gular Kronecker coefficients and plethysms in
2021. How do you feel about going back to the                   geometric complexity theory”4 (with C. Iken-
city you were born to obtain a prize in math-                   meyer), “Asymptotics of symmetric polynomi-
ematics? Do you think that you will be whis-                    als with applications to statistical mechanics
pering, ”yes, I did it, grandma!” while your                    and representation theory”26 (with V. Gorin),
eyes will have been filling with tears?                         and “Hook-length formulas for skew shapes
Panova: Too bad my grandmas died more                           I”18 (with A. Morales and I. Pak). These were
than 20 years ago... It is a great honor to                     all multilayered projects and no problem there
be recognized in my own land31 and it is es-                    was solved at once. For the sake of example,
pecially important to me as an opportunity to                   without being too concrete, I can describe a
introduce my field of algebraic combinatorics                   typical process: first I would try to understand
which is not represented in Bulgaria.                           the objects in the problem usually by interpret-
Mansour: You have some of your paintings on                     ing them geometrically or algebraically (e.g.
your web page. Have you ever planned to be a                    using symmetric functions), and I try to visu-
painter? How would you compare the two cre-                     alize the problem as much as possible. Unlike
ative activities: painting and doing mathemat-                  many combinatorialists, I rarely start with do-
ics? Stendhal syndrome, a strange aesthetic                     ing small examples, I would rather encode the
sickness, is described as a psychosomatic con-                  structure in full generality, look for invariants,
dition involving rapid heartbeat and fainting                   special characteristics, etc. Exploring different
occurring when an individual becomes exposed                    models ultimately could lead to a more “famil-
to artworks of great beauty. Do you think that                  iar” situation that can be handled with exist-
we, mathematicians, experience a similar syn-                   ing tools.
drome when we see an outstanding result or an                   Mansour: Is there a specific problem you
excellent paper? If yes, would you like to offer                have been working on for many years? What
a name to this syndrome?                                        progress have you made?
Panova: Up until college I was planning to                      Panova: Kronecker coefficients have always
be an architect which seemed a good combina-                    been burning a hole in my mind. We have
tion of math and painting. Aesthetics in art                    certainly understood them better throughout
and math could be indeed quite similar to ex-                   the past 10 years, and that research has led
periences. But unlike art, which can be widely                  to many other interesting connections and de-
appreciated, recognizing mathematical beauty                    velopments. At the same time, the problem on
requires more expertise. Personally, my enjoy-                  whether they are in #P or not is still out there
ment of both math and art is in practicing                      with no solution in sight, so it would be hard
them – the joy and satisfaction for finding a                   to tell how close we are.
nice solution are quite similar to those I had                  Mansour: Professor Greta Panova, I would
experienced by expressing on paper the image                    like to thank you for this very interesting in-
in my head.                                                     terview on behalf of the journal Enumerative
Mansour: Would you tell us about your                           Combinatorics and Applications.

 31 but   I can’t be a prophet there per the old saying.

ECA 2:1 (2022) Interview #S3I3                                                                                  7
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