BEGIN:VCALENDAR VERSION:2.0 PRODID:-//Drupal iCal API//EN X-WR-CALNAME:Events items teaser X-WR-TIMEZONE:America/Toronto BEGIN:VTIMEZONE TZID:America/Toronto X-LIC-LOCATION:America/Toronto BEGIN:DAYLIGHT TZNAME:EDT TZOFFSETFROM:-0500 TZOFFSETTO:-0400 DTSTART:20260308T070000 END:DAYLIGHT BEGIN:STANDARD TZNAME:EST TZOFFSETFROM:-0400 TZOFFSETTO:-0500 DTSTART:20251102T060000 END:STANDARD END:VTIMEZONE BEGIN:VEVENT UID:6a570d7bba55e 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:20260715T043259Z END:VEVENT BEGIN:VEVENT UID:6a570d7bbb09f 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:20260715T043259Z END:VEVENT BEGIN:VEVENT UID:6a570d7bbb814 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:20260715T043259Z END:VEVENT BEGIN:VEVENT UID:6a570d7bbbe43 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:20260715T043259Z END:VEVENT BEGIN:VEVENT UID:6a570d7bbc54c 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:20260715T043259Z END:VEVENT BEGIN:VEVENT UID:6a570d7bbcbfe 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:20260715T043259Z END:VEVENT BEGIN:VEVENT UID:6a570d7bbd26a DTSTART;TZID=America/Toronto:20260702T143000 SEQUENCE:0 TRANSP:TRANSPARENT DTEND;TZID=America/Toronto:20260702T153000 URL:https://uwaterloo.ca/combinatorics-and-optimization/events/algebraic-an d-enumerative-combinatorics-seminar-jeronimo-1 SUMMARY:Algebraic and Enumerative combinatorics seminar -Jerónimo\nValenci a-Porras-Type C multiline queues and the open-boundary TASEP CLASS:PUBLIC DESCRIPTION:SPEAKER:\n Jerónimo Valencia-Porras\n\nAFFILIATION:\n Universi ty of Waterloo\n\nLOCATION:\n MC 6460\n\nABSTRACT: The totally asymmetric simple exclusion process (TASEP) is\na finite Markov chain of particles h opping between adjacent sites on a\none-dimensional lattice. The multispec ies TASEP is a generalization in\nwhich particles have different types. Th ese processes have interesting\nconnections to algebraic combinatorics: th e stationary distribution of\nthe TASEP on a circle is connected to Macdon ald polynomials at t=0\,\nwhereas the stationary distribution of the open- boundary TASEP is\nconnected to Koorwinder polynomials at t=0.\n\nMultilin e queues were introduced by Ferrari and Martin (2007) to\ncompute the stat ionary distribution of the multispecies TASEP on a\ncircle. It has been a long-standing open problem to find a\ncombinatorial formula for the statio nary distribution of the\nmultispecies TASEP with open boundaries. Recentl y\, we studied the\ncombinatorics of Ferrari–Martin multiline queues usi ng type A\ncrystals. In this talk\, we use crystals of type C to construct an\nanalog of multiline queues and give a combinatorial formula for the\n stationary distribution of the multispecies open-boundary TASEP for a\ncer tain specialization of the boundary parameters. This is joint work\nwith O lya Mandelshtam.\n\nTHERE WILL BE A PRE-SEMINAR PRESENTING RELEVANT BACKGR OUND AT\nBEGINNING GRADUATE LEVEL STARTING AT 1:30PM IN MC 5417. DTSTAMP:20260715T043259Z END:VEVENT BEGIN:VEVENT UID:6a570d7bbd903 DTSTART;TZID=America/Toronto:20260626T103000 SEQUENCE:0 TRANSP:TRANSPARENT DTEND;TZID=America/Toronto:20260626T113000 URL:https://uwaterloo.ca/combinatorics-and-optimization/events/crypto-readi ng-group-bruce-xu-and-maggie-simmons-hqc SUMMARY:Crypto Reading Group - Bruce Xu and Maggie Simmons-HQC Implementati on\nand Optimisation CLASS:PUBLIC DESCRIPTION:SPEAKER:\n\n Bruce Xu and Maggie Simmons\n\nAFFILIATION:\n Univ ersity of Waterloo\n\nLOCATION:\n MC 5417\n\nABSTRACT:\n\nThis week will cover the implementation and optimization of key\nsub-routines within HQC. We will begin by examining the implementation\nof Reed-Solomon decoding w ithin HQC\, which includes the BCH-view of\nsyndromes\, weighted Newton's identity\, the Berlekamp-Massey algorithm\,\nand more. We will also discus s high-performance polynomial\nmultiplication via the Karatsuba algorithm and hardware optimization. \nReferences: [3] and [4] \n[3] J. Dong\, Y. Ho u\, S. Wang\, L. Sha\, F. Xiao\, Z. Dong\, and J. Lin.\nHIGH: Harnessing G PU Parallelism for Optimized HQC Performance. In\nIACR Cryptology ePrint A rchive\, 2026. \n[4] HQC Team. Hamming Quasi-Cyclic (HQC)\, NIST Submissio n\, 2025. \nA week-by-week plan is outlined at the following\nlink: https ://www.leonardocolo.com/seminars/Spring26.html. DTSTAMP:20260715T043259Z END:VEVENT BEGIN:VEVENT UID:6a570d7bbdff9 DTSTART;TZID=America/Toronto:20260626T153000 SEQUENCE:0 TRANSP:TRANSPARENT DTEND;TZID=America/Toronto:20260626T163000 URL:https://uwaterloo.ca/combinatorics-and-optimization/events/tutte-colloq uium-rutger-campbell-excluded-minors-z3-gainable SUMMARY:Tutte Colloquium -Rutger Campbell-The excluded minors for Z3 -gaina ble\nbiased graphs CLASS:PUBLIC DESCRIPTION:SPEAKER:\n Rutger Campbell\n\nAFFILIATION:\n Institute for Basi c Science\, Korea\n\nLOCATION:\n MC 5501\n\nABSTRACT: A biased graph is a pair (G\,B) consisting of a graph G and\na collection B of “balanced \" cycles in G. Biased graphs arise\nnaturally as the cycles that have ide ntity weight in a group-labelling\nof arcs where opposite arcs have invers e weight. I present an excluded\nminor characterization for biased graphs that have such a\ngroup-labelling over Z3. DTSTAMP:20260715T043259Z END:VEVENT BEGIN:VEVENT UID:6a570d7bbe6cd DTSTART;TZID=America/Toronto:20260625T143000 SEQUENCE:0 TRANSP:TRANSPARENT DTEND;TZID=America/Toronto:20260625T153000 URL:https://uwaterloo.ca/combinatorics-and-optimization/events/algebraic-an d-enumerative-combinatorics-seminar-mike-0 SUMMARY:Algebraic and Enumerative combinatorics seminar -Mike Cummings-Webs \nand smooth components of two column Springer fibers CLASS:PUBLIC DESCRIPTION:SPEAKER:\n Mike Cummings\n\nAFFILIATION:\n University of Waterl oo\n\nLOCATION:\n MC 6460\n\nABSTRACT:  When you encounter an algebraic variety in the wild\, you\nmight ask: What do its components look like? Wh ich components are\nsmooth? How do the components intersect? For Springer fibres\, answers\nto these questions are only known in some very special c ases. This is\nparticularly surprising because other aspects Springer fibr es have\nbeen studied for the past 50 years and they appear throughout\nco mbinatorics and adjacent areas. For just one example:\nHall–Littlewood p olynomials can be obtained from the cohomology of\nSpringer fibres by taki ng graded Frobenius characteristic.\n\nOne classical theorem says that the components of Springer fibers are\nindexed by standard Young tableaux. In this talk\, we will discuss the\nbenefits of instead using webs to index the components in two cases:\nthe \"two row\" case\, and our recent contri butions in the \"two column\"\ncase. We will see that in these cases\, web s both characterize and\ndescribe the smooth components of Springer fibres \, and give a\ngeometric interpretation of rotation of webs.\n\nTHERE WILL BE A PRE-SEMINAR PRESENTING RELEVANT BACKGROUND AT\nBEGINNING GRADUATE LE VEL STARTING AT 1:30PM IN MC 5417. DTSTAMP:20260715T043259Z END:VEVENT END:VCALENDAR