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TZID:America/Toronto
X-LIC-LOCATION:America/Toronto
BEGIN:DAYLIGHT
TZNAME:EDT
TZOFFSETFROM:-0500
TZOFFSETTO:-0400
DTSTART:20260308T070000
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BEGIN:STANDARD
TZNAME:EST
TZOFFSETFROM:-0400
TZOFFSETTO:-0500
DTSTART:20251102T060000
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END:VTIMEZONE
BEGIN:VEVENT
UID:6a5f984514ee6
DTSTART;TZID=America/Toronto:20260724T113000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20260724T123000
URL:https://uwaterloo.ca/combinatorics-and-optimization/events/combopt-read
 inggroup-mahtab-alghasi-local-dyadic-conjecture
SUMMARY:CombOpt ReadingGroup -Mahtab Alghasi-The Local Dyadic Conjecture
CLASS:PUBLIC
DESCRIPTION:SPEAKER:\n\n Mahtab Alghasi\n\nAFFILIATION:\n University of Wat
 erloo\n\nLOCATION:\n MC 6029\n\nABSTRACT: A family of sets $\\mathcal{C}$
  over a finite ground set\n$E(\\mathcal{C})$ is a clutter if no member of 
 $\\mathcal{C}$ properly\ncontains another. A clutter is ideal if its cover
 ing polyhedron is\nintegral. A rational number whose denominator is a powe
 r of two is\ncalled \\emph{dyadic}.\n\nA longstanding conjecture of Paul S
 eymour\, known as the Dyadic\nConjecture\, predicts that\, for every ideal
  clutter\, the dual of the\nset covering linear program admits an optimal 
 solution in which all\nvariables take dyadic values. We present a local ve
 rsion of this\nconjecture and provide evidence for it by proving the propo
 sed local\nstatement for binary clutters under certain assumptions. \nThis
  is joint work with Bertrand Guenin and Levent Tuncel.
DTSTAMP:20260721T160317Z
END:VEVENT
BEGIN:VEVENT
UID:6a5f984516980
DTSTART;TZID=America/Toronto:20260717T113000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20260717T123000
URL:https://uwaterloo.ca/combinatorics-and-optimization/events/combopt-read
 inggroup-noah-weninger-improved-algorithms
SUMMARY:CombOpt ReadingGroup - Noah Weninger-Improved algorithms for\nshort
 est-path network interdiction
CLASS:PUBLIC
DESCRIPTION:SPEAKER:\n Noah Weninger\n\nAFFILIATION:\n University of Waterl
 oo\n\nLOCATION:\n MC 5029\n\nABSTRACT: \n\nIn the shortest-path network i
 nterdiction problem\, the objective is to\nselect a set $X$ of arcs in a d
 irected graph $G=(V\,A)$\, subject to a\nknapsack constraint on $X$\, such
  that the shortest $s$-$t$ path length\nin $(V\,A\\setminus X)$ is maximiz
 ed. We present an improved version of\nthe classic Israeli-Wood Benders co
 vering decomposition (2002). Our\nmethod is based on new upper and lower b
 ounds for the problem which\nintegrate cleanly into the Benders decomposit
 ion\, causing many\niterations to be skipped. Using similar techniques\, w
 e also derive new\ncovering heuristics\, which further reduce the running 
 time. In\ncomputational experiments\, our improved algorithm achieves spee
 dups of\nup to two orders of magnitude. The speedup is most notable on the
  more\ndifficult large\, dense graphs: we can often solve instances on\nco
 mplete graphs with 1000 vertices and uniformly distributed weights\nand co
 sts within a few minutes. \nThis is joint work with Amir Dadpour and Ricar
 do Fukasawa.
DTSTAMP:20260721T160317Z
END:VEVENT
BEGIN:VEVENT
UID:6a5f984517f58
DTSTART;TZID=America/Toronto:20260724T153000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20260724T163000
URL:https://uwaterloo.ca/combinatorics-and-optimization/events/tutte-colloq
 uium-francisco-j-aragon-artacho-graph-based
SUMMARY:Tutte Colloquium -Francisco J. Aragón Artacho-Graph-based splittin
 g\nalgorithms for optimization and feasibility problems
CLASS:PUBLIC
DESCRIPTION:SPEAKER:\n Francisco J. Aragón Artacho\n\nAFFILIATION:\n Unive
 rsity of Alicante\n\nLOCATION:\n MC 5501\n\nABSTRACT: When an optimizatio
 n problem is structured\, it is normally\nadvantageous to use this feature
  when designing algorithms to solve\nit. Following the divide-and-conquer 
 paradigm\, splitting algorithms\niteratively solve simpler problems that a
 re defined by separately\nusing some parts of the original problem. In thi
 s talk\, we will recall\nsome classical methods and present some recent ad
 vances in this\nsubject\, paying special attention to splitting methods de
 vised by\ngraphs.
DTSTAMP:20260721T160317Z
END:VEVENT
BEGIN:VEVENT
UID:6a5f9845193df
DTSTART;TZID=America/Toronto:20260723T143000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20260723T153000
URL:https://uwaterloo.ca/combinatorics-and-optimization/events/algebraic-an
 d-enumerative-combinatorics-seminar-alexandre
SUMMARY:Algebraic and Enumerative combinatorics seminar -Alexandre Zotine-A
 \npipe dream framework for orbital varieties of type M² = 0
CLASS:PUBLIC
DESCRIPTION:SPEAKER:\n Alexandre Zotine\n\nAFFILIATION:\n University of Saa
 rland\n\nLOCATION:\n MC 5479\n\nABSTRACT: An orbital scheme D of type M²
  = 0 is the closure of a\nconjugacy class of some set of n × n upper tria
 ngular matrices which\nare nilpotent of order 2. The geometric components 
 of the orbit scheme\nare called orbital varieties of type M² = 0\, and re
 cently their\ninvariants have been connected to statistical mechanics. In 
 the\nsetting of M² = 0\, there are combinatorial methods for studying the
 se\ninvariants via the action of the Borel group of upper triangular\ninve
 rtible matrices. In this talk\, we introduce a new pipe dream\nframework f
 or computing and understanding these invariants. This is\njoint work with 
 Megumi Harada\, Illya Kierkosz\, Allen Knutson\, Emma\nNaguit\, Brett Nass
 erden\, Naveena Rangunathan\, and Adam van Tuyl.\n\nTHERE WILL BE A PRE-SE
 MINAR PRESENTING RELEVANT BACKGROUND AT\nBEGINNING GRADUATE LEVEL STARTING
  AT 1:30PM IN MC 5417.
DTSTAMP:20260721T160317Z
END:VEVENT
BEGIN:VEVENT
UID:6a5f984519f47
DTSTART;TZID=America/Toronto:20260717T153000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20260717T163000
URL:https://uwaterloo.ca/combinatorics-and-optimization/events/tutte-colloq
 uium-audrey-beliveau-combinatorial-structure-and-0
SUMMARY:Tutte Colloquium -Audrey Béliveau-Combinatorial Structure and\nAlg
 orithms for Treatment Rankings
CLASS:PUBLIC
DESCRIPTION:SPEAKER:\n Audrey Béliveau\n\nAFFILIATION:\n University of Wat
 erloo\n\nLOCATION:\n MC 5501\n\nABSTRACT: \n\nNetwork meta-analysis (NMA)
  enables the comparison of multiple medical\ninterventions by combining ev
 idence on their efficacy or safety across\nclinical trials. Although these
  models produce rich probabilistic\ninformation about how treatments rank\
 , what practitioners often want\nare simple\, interpretable summaries\; fo
 r example\, whether a treatment\nis likely among the best\, or whether one
  option is likely to\noutperform another. \nThe challenge is that\, with n
  treatments\, the number of possible\nquestions one can ask about permutat
 ions\, combinations\, or partial\norderings of various subsets of treatmen
 ts grows exponentially. This\nleads to a large but highly structured combi
 natorial space\, making\nexhaustive evaluation infeasible. \nWe develop al
 gorithmic methods to explore this space efficiently and\nto identify all b
 inary treatment hierarchy statements whose posterior\nprobability exceeds 
 a specified threshold (e.g.\, 95%). Our approach\nexploits structure in th
 e ranking space to avoid redundant\ncomputations and then prunes conclusio
 ns that are logically implied by\nothers\, yielding a concise and non-redu
 ndant set of results. We\nillustrate the approach on an NMA of diabetes tr
 eatments.
DTSTAMP:20260721T160317Z
END:VEVENT
BEGIN:VEVENT
UID:6a5f98451af59
DTSTART;TZID=America/Toronto:20260710T103000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20260710T113000
URL:https://uwaterloo.ca/combinatorics-and-optimization/events/crypto-readi
 ng-group-maggie-simmons-hqc-implementation-and
SUMMARY:Crypto Reading Group - Maggie Simmons-HQC Implementation and\nOptim
 ization
CLASS:PUBLIC
DESCRIPTION:SPEAKER:\n\n Maggie Simmons\n\nAFFILIATION:\n University of Wat
 erloo\n\nLOCATION:\n MC 6029\n\nABSTRACT:\n\nThis week will cover the impl
 ementation and optimization of key\nsub-routines within HQC. We will begin
  by examining the implementation\nof Reed-Solomon decoding within HQC\, wh
 ich includes the BCH-view of\nsyndromes\, weighted Newton's identity\, the
  Berlekamp-Massey algorithm\,\nand more. We will also discuss high-perform
 ance polynomial\nmultiplication via the Karatsuba algorithm and hardware o
 ptimization. \nReferences: [3] and [4] \n[3] J. Dong\, Y. Hou\, S. Wang\, 
 L. Sha\, F. Xiao\, Z. Dong\, and J. Lin.\nHIGH: Harnessing GPU Parallelism
  for Optimized HQC Performance. In\nIACR Cryptology ePrint Archive\, 2026.
  \n[4] HQC Team. Hamming Quasi-Cyclic (HQC)\, NIST Submission\, 2025. \nA 
 week-by-week plan is outlined at the following\nlink: https://www.leonard
 ocolo.com/seminars/Spring26.html.
DTSTAMP:20260721T160317Z
END:VEVENT
BEGIN:VEVENT
UID:6a5f98451c207
DTSTART;TZID=America/Toronto:20260709T143000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20260709T153000
URL:https://uwaterloo.ca/combinatorics-and-optimization/events/algebraic-an
 d-enumerative-combinatorics-seminar-oliver
SUMMARY:Algebraic and Enumerative combinatorics seminar -Oliver\nPechenik-R
 evenge of the increasing tableau dynamics
CLASS:PUBLIC
DESCRIPTION:SPEAKER:\n Oliver Pechenik\n\nAFFILIATION:\n University of Wate
 rloo\n\nLOCATION:\n MC 6460\n\nABSTRACT: Standard tableaux are certain gr
 ids of numbers that lead a\ndouble life in algebraic combinatorics\, with 
 distinct roles in\ngeometry and in representation theory. Extending the ge
 ometry to\nK-theory led to a corresponding extension of the combinatorics 
 to a\ntheory of increasing tableaux. I will discuss a longstanding plot by
 \nsuch tableaux to prevent me from explicating their combinatorial\ndynami
 cs. Despite their reticence\, we seem to be uncovering that these\ntableau
 x also have a mysterious second life in representation theory.\n\nTHERE WI
 LL BE A PRE-SEMINAR PRESENTING RELEVANT BACKGROUND AT\nBEGINNING GRADUATE 
 LEVEL STARTING AT 1:30PM IN MC 5417.
DTSTAMP:20260721T160317Z
END:VEVENT
BEGIN:VEVENT
UID:6a5f98451d381
DTSTART;TZID=America/Toronto:20260710T113000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20260710T123000
URL:https://uwaterloo.ca/combinatorics-and-optimization/events/combopt-read
 inggroup-nathan-benedetto-proenca-why-are-sdp
SUMMARY:CombOpt ReadingGroup - Nathan Benedetto Proenca-Why are SDP Roundi
 ng\nAlgorithms Randomized?
CLASS:PUBLIC
DESCRIPTION:SPEAKER:\n\n Nathan Benedetto Proenca\n\nAFFILIATION:\n Univers
 ity of Waterloo\n\nLOCATION:\n MC 6029\n\nABSTRACT: Randomization is a po
 werful technique within theoretical\ncomputer science. There is strong th
 eoretical picture studying\ndistinct complexity models with access to ran
 dom bits\, in particular\nfocused on what types of algorithms can be de-r
 andomized. This\ndiscussion will not venture into this part of the litera
 ture\, rather\nquestioning an implicit assumption present when discussing
  the need\nfor random bits. Why is randomness helpful at all\, in partic
 ular in\nthe design of rounding algorithms in the SDP literature? Grante
 d\,\nthe value of randomness in other contexts is quite explicit. For\ne
 xample\, a quicksort implementation uses randomization to avoid worst\nca
 se inputs. The probabilistic method allows for simple constructions\nof c
 omplex objects by harvesting complexity from a randomness source.\nBut wh
 at purpose does randomness serve when rounding a SDP solution\ninto a sol
 ution to a NP-hard problem? Why Goemans and Williamson had\nto use a rand
 om hyperplane to turn vectors in the hypersphere into a\nedge-cut in a gr
 aph? This talk attempts to answer this question by\npresenting a couple 
 of theorems which connect the existence of\nrandomized rounding algorithm
 s to cornerstone results in functional\nanalysis.
DTSTAMP:20260721T160317Z
END:VEVENT
BEGIN:VEVENT
UID:6a5f98451e54a
DTSTART;TZID=America/Toronto:20260703T153000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20260703T163000
URL:https://uwaterloo.ca/combinatorics-and-optimization/events/tutte-colloq
 uium-oliver-pechenik-dynamics-increasing
SUMMARY:Tutte Colloquium -Oliver Pechenik-Dynamics of Increasing Tableaux
CLASS:PUBLIC
DESCRIPTION:SPEAKER:\n Oliver Pechenik\n\nAFFILIATION:\n University of Wate
 rloo\n\nLOCATION:\n MC 5501\n\nABSTRACT: Standard tableaux are certain gr
 ids of numbers that lead a\ndouble life in algebraic combinatorics\, with 
 distinct roles in\ngeometry and in representation theory. Extending the ge
 ometry to\nK-theory led to a corresponding extension of the combinatorics 
 to a\ntheory of increasing tableaux. I will discuss a long and ongoing\npr
 ogram to explicate the combinatorial dynamics of these tableaux\,\nwhich s
 eems to be revealing that they also have a mysterious second\nlife in repr
 esentation theory. Despite the algebraic connections\, the\ncore problem i
 s fundamentally combinatorial: to give a sufficiently\ngood bijection betw
 een tableaux and a set of planar diagrams. 
DTSTAMP:20260721T160317Z
END:VEVENT
BEGIN:VEVENT
UID:6a5f984520a61
DTSTART;TZID=America/Toronto:20260626T113000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20260626T123000
URL:https://uwaterloo.ca/combinatorics-and-optimization/events/combopt-read
 inggroup-rian-neogi-multidimensional-budget
SUMMARY:CombOpt ReadingGroup - Rian Neogi-Multidimensional Budget-feasible\
 nmechanism design
CLASS:PUBLIC
DESCRIPTION:SPEAKER:\n\n Rian Neogi\n\nAFFILIATION:\n University of Waterlo
 o\n\nLOCATION:\n MC 6029\n\nABSTRACT:  \n\nIn budget-feasible mechanism 
 design\, there is a set of items U. A\nbuyer wishes to purchase a set of i
 tems from the sellers of maximum\nvalue\, where the value of a subset S of
  items is provided by a\nvaluation function v. Each element e is held by a
  distinct seller\, who\nincurs a private cost c_e for supplying her item. 
 The buyer also has a\nbudget of B on the total payments made to the seller
 s. The private\ncosts c_e are known only to the sellers\, and not to the b
 uyer. Each\nseller e reports a cost r_e to the mechanism\, which may or ma
 y not be\nequal to her true cost c_e. As a result\, a seller may choose to
 \nmisreport her cost if she sees that she is better off when doing so\n(fo
 r example\, the mechanism might be giving her a higher payment under\nthe 
 misreported cost).  \nBudget-feasible mechanisms have been well-studied o
 ver the past 15\nyears. In this talk\, we will introduce a generalization 
 of the\nsetting\, where each agent can now hold multiple items. This\ngene
 ralizes the problem into what is known as a multi-parameter\ndomain\, whic
 h brings about several complications\, including strong\nimpossibility res
 ults with respect to the typical benchmark of the\nalgorithmic optimum. In
  lieu of these impossibility results\, we\npropose a novel benchmark for t
 he setting. We prove positive results\nwith respect to this new benchmark\
 , qualitatively matching prior\nresults in single-parameter budget-feasibl
 e mechanism design. \nThis is joint work with Kanstantsin Pashkovich and C
 haitanya Swamy\,\nand is to appear in EC 2026.
DTSTAMP:20260721T160317Z
END:VEVENT
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