BEGIN:VCALENDAR
VERSION:2.0
PRODID:researchseminars.org
CALSCALE:GREGORIAN
X-WR-CALNAME:researchseminars.org
BEGIN:VEVENT
SUMMARY:Alba Málaga (Université de Lorraine)
DTSTART:20201029T080000Z
DTEND:20201029T090000Z
DTSTAMP:20260430T041644Z
UID:SageDays110/1
DESCRIPTION:Title: Polyhedral flat tori\nby Alba Málaga (Université de Lorraine) as
part of Global Virtual SageDays 110\n\n\nAbstract\nWhen you first meet th
e flat torus in the classroom\, often it is the square flat torus: the quo
tient of a square by an orientation preserving identification of the oppos
ite sides. Informally\, we could say that after gluing the opposite sides
of a square\, we get the (square) flat torus. This abstract "gluing" const
ruction can actually be done starting with any parallelogram\, giving rise
to a large family of flat tori\, which itself has a rich geometric struct
ure.\nThe precise mathematical construction of the gluing of the flat tori
poses no particular issue. However\, it is trickier to realize an isometr
ic embedding of such a flat torus in euclidean 3-space. At this talk\, I w
ill present a particular type of embedding\, an origami embedding\, i.e.\,
a continuous\, piecewise linear\, isometric embedding of the flat torus i
nto the euclidean 3-space. This can be done through paper folding\, and we
had actually computed\, using SageMath\, explicit layouts for a large fam
ily of flat paper tori.\nThis is joint work with Samuel Lelievre and Pierr
e Arnoux.\n
LOCATION:https://researchseminars.org/talk/SageDays110/1/
END:VEVENT
BEGIN:VEVENT
SUMMARY:David Coudert (COATI)
DTSTART:20201029T090000Z
DTEND:20201029T100000Z
DTSTAMP:20260430T041644Z
UID:SageDays110/2
DESCRIPTION:Title: On the Flinders Hamiltonian Cycle Problem Challenge\nby David Coud
ert (COATI) as part of Global Virtual SageDays 110\n\n\nAbstract\nOn Septe
mber 30\, 2015\, the Graph Theory research group at Flinders University in
Adelaide\, Australia\, launched an open competition called the Flinders H
amiltonian Cycle Project (FHCP) Challenge. It provided 1001 large graphs (
up to 9528 vertices) and asked participants to find\, in each of these gra
phs\, a Hamiltonian Cycle\, i.e. a cycle passing through the edges of this
graph and visiting all its vertices once and only once. This is a classic
problem in graph theory\, considered very difficult to solve (NP-Complete
). It is the decision version of the famous traveling salesman problem (TS
P)\, a NP-hard optimization problem.\n\nTo win this challenge\, one had to
be the first team to find a solution for all the graphs proposed within t
he competition deadline (1 year). The objective of the organizers was to m
ake a "state of the art" of known methods and to measure their effectivene
ss in practice. The competition was also intended to identify the really d
ifficult graphs\, i.e. those that no one could solve.\n\nIn this talk\, we
will presents the various methods of graph exploration\, decomposition an
d optimization that the team of Nathann Cohen and David Coudert used to wi
n this challenge by solving 985 instances.\n
LOCATION:https://researchseminars.org/talk/SageDays110/2/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Viviane Pons (Paris-Saclay University)
DTSTART:20201029T110000Z
DTEND:20201029T120000Z
DTSTAMP:20260430T041644Z
UID:SageDays110/3
DESCRIPTION:Title: Presenting the multipolynomial bases package\nby Viviane Pons (Par
is-Saclay University) as part of Global Virtual SageDays 110\n\n\nAbstract
\nIn this talk\, we present an external Sage package to work on multivaria
te polynomials seen as an algebra over integer vectors (the exponents). Th
is allows for manipulation of divided differences operators and the defini
tion of many bases of multivariate polynomials such as the Schubert polyno
mials\, Grothendieck\, and Demazure Characters.\n
LOCATION:https://researchseminars.org/talk/SageDays110/3/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ben Hutz (St Louis University)
DTSTART:20201029T150000Z
DTEND:20201029T160000Z
DTSTAMP:20260430T041644Z
UID:SageDays110/6
DESCRIPTION:Title: Automorphisms for Endomorphisms of Projective Space\nby Ben Hutz (
St Louis University) as part of Global Virtual SageDays 110\n\n\nAbstract\
nThis talk focuses on automorphisms of endomorphisms of\nprojective space.
The first portion will address improving on the\nalgorithm in Sage to com
pute all automorphisms of a given endomorphism.\nThe second portion will f
ind all endomorphisms of the projective line of\ndegree 3 or 4 with a non-
trivial automorphism. This is primarily a\ncomputational problem and relie
s heavily on the dynamical system and\nalgebraic geometry functionality in
Sage.\n\nTo get the password for the zoom meeting\, evaluate print(bytes.
fromhex('53537433547a4d314f54646861476c4b5748464f567a465652586450647a3039'
).decode()) in Python 3 or go to https://zulip.sagemath.org/#narrow/stream
/128-sd110.\n
LOCATION:https://researchseminars.org/talk/SageDays110/6/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Éric Gourgoulhon (Observatoire de Paris)
DTSTART:20201029T160000Z
DTEND:20201029T170000Z
DTSTAMP:20260430T041644Z
UID:SageDays110/7
DESCRIPTION:Title: Pseudo-Riemannian manifolds in SageMath: the Schwarzschild spacetime e
xample\nby Éric Gourgoulhon (Observatoire de Paris) as part of Global
Virtual SageDays 110\n\nAbstract: TBA\n\nTo get the password for the zoom
meeting\, evaluate print(bytes.fromhex('53537433547a4d314f54646861476c4b5
748464f567a465652586450647a3039').decode()) in Python 3 or go to https://z
ulip.sagemath.org/#narrow/stream/128-sd110.\n
LOCATION:https://researchseminars.org/talk/SageDays110/7/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Wencin Poh (UC Davis)
DTSTART:20201029T190000Z
DTEND:20201029T200000Z
DTSTAMP:20260430T041644Z
UID:SageDays110/8
DESCRIPTION:Title: Development of code in combinatorics for Sage\nby Wencin Poh (UC D
avis) as part of Global Virtual SageDays 110\n\n\nAbstract\nSay that you h
ave a cool computational package in combinatorics that you would like to m
ake \navailable in Sage. How would you go about doing this? I'll present m
y personal experience \nin developing code for Sage in past projects and s
hare good practices on how you could \ncollaborate and contribute as well.
\n\nTo get the password for the zoom meeting\, evaluate print(bytes.fromhe
x('736167656d617468').decode()) in Python 3 or go to https://zulip.sagemat
h.org/#narrow/stream/128-sd110.\n
LOCATION:https://researchseminars.org/talk/SageDays110/8/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jessica Striker (North Dakota State University)
DTSTART:20201029T200000Z
DTEND:20201029T210000Z
DTSTAMP:20260430T041644Z
UID:SageDays110/9
DESCRIPTION:Title: Tableau and toggle dynamics in Sage – computation and visualization<
/a>\nby Jessica Striker (North Dakota State University) as part of Global
Virtual SageDays 110\n\n\nAbstract\nI will discuss the dual uses of Sage f
or computation and visualization of combinatorial objects through examples
in dynamical algebraic combinatorics.\n\nTo get the password for the zoom
meeting\, evaluate print(bytes.fromhex('736167656d617468').decode()) in P
ython 3 or go to https://zulip.sagemath.org/#narrow/stream/128-sd110.\n
LOCATION:https://researchseminars.org/talk/SageDays110/9/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Tom Roby (University of Connecticut)
DTSTART:20201029T210000Z
DTEND:20201029T220000Z
DTSTAMP:20260430T041644Z
UID:SageDays110/10
DESCRIPTION:Title: Dynamical Algebraic Combinatorics & Noncommutative Needs\nby Tom
Roby (University of Connecticut) as part of Global Virtual SageDays 110\n\
n\nAbstract\nThanks to the work of many people over decades\, Sagemath is
endowed with a large number of methods in algebraic combinatorics. This m
akes it a natural place to run experiments in the relatively young subfiel
d of dynamical algebraic combinatorics (DAC)\, which explores the dynamics
of actions on sets of discrete combinatorial objects. Examples include p
romotion of linear extensions\, rowmotion of order ideals\, and their lift
ings to polytopes\, birational maps\, and even the noncommutative setting.
\n\nThis talk will be an action-packed introduction to these ideas\, highl
ighting some relevant code developed with Darij Grinberg and some workshee
ts by my student Matthew Plante. While experiments in Sagemath were essen
tial in helping conjecture a formula for birational rowmotion (now a theor
em with Gregg Musiker) in terms of non-intersecting lattice paths\, develo
ping an analogue for the noncommutative setting is hampered by the current
lack of methods for handling expressions with skew-field variables.\n\nTo
get the password for the zoom meeting\, evaluate print(bytes.fromhex('736
167656d617468').decode()) in Python 3 or go to https://zulip.sagemath.org/
#narrow/stream/128-sd110.\n
LOCATION:https://researchseminars.org/talk/SageDays110/10/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Matthias Koeppe (UC Davis)
DTSTART:20201030T000000Z
DTEND:20201030T010000Z
DTSTAMP:20260430T041644Z
UID:SageDays110/11
DESCRIPTION:Title: Modularization and pip-installability of the Sage library\nby Mat
thias Koeppe (UC Davis) as part of Global Virtual SageDays 110\n\n\nAbstra
ct\nI will explain the ongoing project to modularize the Sage library into
separate\, pip-installable distributions. \n\nMeta-ticket #29705 (https:
//trac.sagemath.org/ticket/29705) outlines the work completed in Sage 9.2
and planned for Sage 9.3 and 9.4.\n\nTo get the password for the zoom meet
ing\, evaluate print(bytes.fromhex('736167656d617468').decode()) in Python
3 or go to https://zulip.sagemath.org/#narrow/stream/128-sd110.\n
LOCATION:https://researchseminars.org/talk/SageDays110/11/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Isuru Fernando (University of Illinois at Urbana-Champaign)
DTSTART:20201030T010000Z
DTEND:20201030T020000Z
DTSTAMP:20260430T041644Z
UID:SageDays110/12
DESCRIPTION:Title: conda\, conda-forge and sagemath\nby Isuru Fernando (University o
f Illinois at Urbana-Champaign) as part of Global Virtual SageDays 110\n\n
\nAbstract\nSagemath has a lot of dependencies for the underlying python l
ibrary sage. These dependencies take a lot of time to compile sometimes ev
en days and compiling sometimes fail with new OS updates.\nIn this talk th
e conda package manager\, a cross platform package manager for Linux\, OSX
and Windows will be introduced and how conda can be used for providing de
pendencies for sage will be discussed. We will also talk about conda-forge
\, a community powered conda package repository where community members ca
n add new conda packages and introduce changes to existing ones.\n\nTo get
the password for the zoom meeting\, evaluate print(bytes.fromhex('7361676
56d617468').decode()) in Python 3 or go to https://zulip.sagemath.org/#nar
row/stream/128-sd110.\n
LOCATION:https://researchseminars.org/talk/SageDays110/12/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Anna Puskas (University of Queensland)
DTSTART:20201030T050000Z
DTEND:20201030T060000Z
DTSTAMP:20260430T041644Z
UID:SageDays110/13
DESCRIPTION:Title: Double affine Hecke algebras and the Bruhat order\nby Anna Puskas
(University of Queensland) as part of Global Virtual SageDays 110\n\n\nAb
stract\nThe Iwahori-Hecke algebra is a fundamental tool in the representat
ion theory of $p$-adic groups. Experimentation with Sagemath is a useful t
ool in developing an intuition for related phenomena.\n\nWe will review th
e Coxeter and Bernstein presentation of the affine Iwahori-Hecke algebra a
nd the notion of a ``Tits cone'' double affine Hecke algebra introduced by
Braverman\, Kazhdan and Patnaik. We will discuss features of these algebr
as\, and present some conjectures in the double affine context. This is jo
int work in progress with Dinakar Muthiah.\n\nThe talk aims to be accessib
le to those familiar with the representation theory of finite dimensional
Lie algebras. It proposes to illustrate the potential benefits of having r
obust tools in Sagemath for affine Hecke algebra computations.\n
LOCATION:https://researchseminars.org/talk/SageDays110/13/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Amri Prasad (IMSc)
DTSTART:20201030T060000Z
DTEND:20201030T070000Z
DTSTAMP:20260430T041644Z
UID:SageDays110/14
DESCRIPTION:Title: Computing (with) character polynomials\nby Amri Prasad (IMSc) as
part of Global Virtual SageDays 110\n\n\nAbstract\nA polynomial $p$ in var
iables $X_1\, X_2\, \\ldots$ yields a class function on the\nsymmetric gro
up $S_n$ for each n by evaluating the variable $X_i$ as the\nnumber
of $i$ cycles in a permutation.\n\nThere are many interesting families of
representations whose characters\ncan be expressed in terms of such polyn
omials. The Specht modules of\npadded partitions (see Garsia and Goupil:\n
http://dx.doi.org/10.1016/j.jcta.2019.02.019) and Weyl functor (also\ncall
ed Schur functors\; see https://arxiv.org/abs/2001.04112) are two such\nfa
milies. In general families arising from FI-modules have eventually\npolyn
omial characters (Church\, Ellenberg\, and Farb\nhttp://dx.doi.org/10.1215
/00127094-3120274).\n\nCharacter computations can be nicely done in Sage u
sing the moment formula\n(Theorem 2.3 of https://arxiv.org/abs/2001.04112)
allowing for easy\ncomputation of restriction coefficients\, Kronecker co
efficients\, and their\nstable versions.\n
LOCATION:https://researchseminars.org/talk/SageDays110/14/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Katja Berčič (University of Ljubljana)
DTSTART:20201030T080000Z
DTEND:20201030T090000Z
DTSTAMP:20260430T041644Z
UID:SageDays110/15
DESCRIPTION:Title: Data in mathematics\nby Katja Berčič (University of Ljubljana)
as part of Global Virtual SageDays 110\n\n\nAbstract\nIn this talk\, I wil
l present a slice of the landscape of data appearing in mathematics\, focu
sed on connections with computer algebra systems. There are several datab
ases that are integrated with Sagemath\, but I will focus on the potential
to streamline that for new datasets.\n
LOCATION:https://researchseminars.org/talk/SageDays110/15/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Reimundo Heluani (IMPA)
DTSTART:20201030T100000Z
DTEND:20201030T110000Z
DTSTAMP:20260430T041644Z
UID:SageDays110/16
DESCRIPTION:Title: Vertex algebras in SageMath\nby Reimundo Heluani (IMPA) as part o
f Global Virtual SageDays 110\n\n\nAbstract\nWe review a proposed implemen
tation of vertex algebras on SageMath (ticket #29610). We will briefly des
cribe the main mathematical objects involved and go straight to the packag
e usage. We will cover basic operations\, ideals\, quotients\, classical l
imits\, enveloping algebras\, arc algebras\, singular support embedding et
c.\n
LOCATION:https://researchseminars.org/talk/SageDays110/16/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Simon King (Friedrich-Schiller-Univerität Jena)
DTSTART:20201030T110000Z
DTEND:20201030T120000Z
DTSTAMP:20260430T041644Z
UID:SageDays110/17
DESCRIPTION:Title: Computing Modular Cohomology Rings of Finite Groups with SageMath
\nby Simon King (Friedrich-Schiller-Univerität Jena) as part of Global Vi
rtual SageDays 110\n\n\nAbstract\nI'll start with an introduction to the m
athematical requirements for the computation of cohomology rings of finite
groups. I'll show what examples can be tackled by the `p_group_cohomology
` spkg and how SageMath's infrastructure is used in the process. The stron
g interrelation with SageMath's infrastructure occasionally led to mainten
ance problems. I'll discuss current attempts to restructure the spkg to ma
ke it easier maintainable.\n
LOCATION:https://researchseminars.org/talk/SageDays110/17/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Michael Jung (Vrije Universiteit)
DTSTART:20201030T130000Z
DTEND:20201030T140000Z
DTSTAMP:20260430T041644Z
UID:SageDays110/18
DESCRIPTION:Title: Characteristic Classes in SageMath\nby Michael Jung (Vrije Univer
siteit) as part of Global Virtual SageDays 110\n\n\nAbstract\nWe talk abou
t my contribution of characteristic classes to SageManifold. Characteristi
c classes are useful to determine geometric invariants such as the Euler c
haracteristic or the index of the Dirac operator. We start with mixed diff
erential forms and introduce characteristic classes via Chern—Weil theor
y. In between\, we present examples given in Sage. After we have sketched
the current implementation\, we discuss possible improvements in terms of
computational speed-up\, usability and further future prospects.\n\nThe ta
lk assumes basic knowledge in differential geometry and possibly vector bu
ndles.\n
LOCATION:https://researchseminars.org/talk/SageDays110/18/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Guy Blachar (Bar-Ilan University)
DTSTART:20201030T140000Z
DTEND:20201030T150000Z
DTSTAMP:20260430T041644Z
UID:SageDays110/19
DESCRIPTION:Title: Commutative and Noncommutative Groebner Bases\nby Guy Blachar (Ba
r-Ilan University) as part of Global Virtual SageDays 110\n\n\nAbstract\nG
roebner bases are a subject with various applications in many fields of ma
thematics\, such as algebraic geometry\, algebraic topology\, graph colori
ngs and integer programming. In this talk we present the notion of Groebne
r bases in the commutative and in the noncommutative settings\, showing so
me of their applications and discussing the current implementations in Sag
eMath.\n
LOCATION:https://researchseminars.org/talk/SageDays110/19/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Tobias Rossmann (NUI Galway)
DTSTART:20201030T151500Z
DTEND:20201030T161500Z
DTSTAMP:20260430T041644Z
UID:SageDays110/20
DESCRIPTION:Title: Zeta functions of groups\, algebras\, and modules: toric computations
\nby Tobias Rossmann (NUI Galway) as part of Global Virtual SageDays 1
10\n\n\nAbstract\n"Zeta" is a package for SageMath which provides methods
for computing various types of zeta functions arising from algebraic count
ing problems (e.g. the enumeration of subgroups\, submodules\, or represen
tations). In this talk\, I will provide a (biased) introduction to this ar
ea and I will give an overview of the techniques underpinning Zeta.\n
LOCATION:https://researchseminars.org/talk/SageDays110/20/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Martin Rubey (Universität Wien)
DTSTART:20201030T170000Z
DTEND:20201030T180000Z
DTSTAMP:20260430T041644Z
UID:SageDays110/21
DESCRIPTION:Title: Species (not) in SageMath\nby Martin Rubey (Universität Wien) as
part of Global Virtual SageDays 110\n\n\nAbstract\nI will survey what com
binatorial species can do for you and how to play with them in SageMath. I
will also present several desirable extensions of the features that are c
urrently provided. Some of these would be easy to implement\, but tremendo
usly increase the usefulness of the package: interaction with group action
s\, quotients\, various decompositions\, more operations\, access to rando
m generation\, multivariate species\, to name a few\, see https://trac.sagemath.org/ticket/30727 <
/a> for a summary.\n
LOCATION:https://researchseminars.org/talk/SageDays110/21/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Miguel Marco-Buzunariz (Universidad de Zaragoza)
DTSTART:20201030T180000Z
DTEND:20201030T190000Z
DTSTAMP:20260430T041644Z
UID:SageDays110/22
DESCRIPTION:Title: Proposal for step-by-step integrals in SageMath\nby Miguel Marco-
Buzunariz (Universidad de Zaragoza) as part of Global Virtual SageDays 110
\n\n\nAbstract\nMany students that are learning the integration of functio
ns use resources\nthat provide them the steps to follow in the calculation
. Right now\, SageMath\ndoesn't provide such a functionality\, even if sym
py (included in SageMath) has\nthe needed building blocks.\nIn the talk\,
I will present a proposal of implementation (being worked on\n#28415)\, an
d would like to discuss different possible user interfaces for that.\n
LOCATION:https://researchseminars.org/talk/SageDays110/22/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Gark Garcia\, Mauricio Matera\, Rocky Bernstein
DTSTART:20201030T190000Z
DTEND:20201030T200000Z
DTSTAMP:20260430T041644Z
UID:SageDays110/23
DESCRIPTION:Title: Mathics: a free and open source alternative to Mathematica\nby Ga
rk Garcia\, Mauricio Matera\, Rocky Bernstein as part of Global Virtual Sa
geDays 110\n\n\nAbstract\nMathics is an Open Source implementation of the
Wolfram Language (https://en.wikipedia.org/wiki/Wolfram_Language)\, includ
ing a Python library\, a command-line interpreter\, and a Django-based we
b interface. In this talk\, we are going to present the status of the Math
ics project\, including some details of the recent release 1.1 and future
perspectives.\n
LOCATION:https://researchseminars.org/talk/SageDays110/23/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jianping Pan (UC Davis)
DTSTART:20201030T220000Z
DTEND:20201030T230000Z
DTSTAMP:20260430T041644Z
UID:SageDays110/25
DESCRIPTION:Title: Sage Experimentation with stable Grothendieck polynomials\nby Jia
nping Pan (UC Davis) as part of Global Virtual SageDays 110\n\n\nAbstract\
nIn this talk\, I will talk about how my project A crystal on decreasing f
actorizations in the 0-Hecke monoid (arXiv:1911.08732) with my coauthors J
ennifer Morse\, Wencin Poh and Anne Schilling developed with experimentati
on in SageMath. In our project\, we introduced a crystal on combinatorial
objects underlying the stable Grothendieck polynomials of skew shapes. Thi
s crystal is a K-theoretic generalization of the Morse-Schilling crystal o
n decreasing factorizations in the symmetric group. We proved that it inte
rtwines with the crystal on set-valued tableaux introduced by Monical\, Pe
chenik\, and Scrimshaw (through the residue map). We also define a new ins
ertion algorithm that intertwines with our crystal\, with surprising conne
ctions to the Hecke insertion algorithm and the uncrowding algorithm for s
et-valued tableaux.\n
LOCATION:https://researchseminars.org/talk/SageDays110/25/
END:VEVENT
END:VCALENDAR