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:6aadb64acfc6d DTSTART;TZID=America/Toronto:20260925T153000 SEQUENCE:0 TRANSP:TRANSPARENT DTEND;TZID=America/Toronto:20260925T163000 URL:https://uwaterloo.ca/combinatorics-and-optimization/events/generating-a nd-utilizing-various-types-negative-dependence-2 SUMMARY:Generating and utilizing various types of negative dependence CLASS:PUBLIC DESCRIPTION:SPEAKER:\n Aravind Srinivasan\n\nAFFILIATION:\n University of M aryland\n\nLOCATION:\n MC 5501\n\nABSTRACT: Various notions of negative de pendence arise naturally\nand/or are desirable in various random processes and randomized\nalgorithms. We survey how to generate and utilize a few s uch notions\nof negative dependence\, and sketch applications to concentra tion\ninequalities\, fairness\, and approximation algorithms. DTSTAMP:20260918T220810Z END:VEVENT BEGIN:VEVENT UID:6aadb64ad3fe8 DTSTART;TZID=America/Toronto:20260923T100000 SEQUENCE:0 TRANSP:TRANSPARENT DTEND;TZID=America/Toronto:20260923T110000 URL:https://uwaterloo.ca/combinatorics-and-optimization/events/introduction -quantum-computing SUMMARY:Introduction to Quantum Computing CLASS:PUBLIC DESCRIPTION:Abstract: For this term's reading group we will be hosting a st udy\ngroup on quantum tools in cryptography. A week-by-week plan outline\n [https://www.leonardocolo.com/seminars/Fall26.html]. For the first\nweek\, we start with a motivation on quantum computing including the\nbasic defi nitions and discussion on complexity classes. This will\nserve as a elemen tary foundation for the rest of the reading group. DTSTAMP:20260918T220810Z END:VEVENT BEGIN:VEVENT UID:6aadb64ad50ea DTSTART;TZID=America/Toronto:20260918T153000 SEQUENCE:0 TRANSP:TRANSPARENT DTEND;TZID=America/Toronto:20260918T163000 URL:https://uwaterloo.ca/combinatorics-and-optimization/events/many-mirrors -grassmannian-and-beyond SUMMARY:The many mirrors of the Grassmannian (and beyond) CLASS:PUBLIC DESCRIPTION:SPEAKER:\n Elana Kalashnikov\n\nAFFILIATION:\n University of Wa terloo\n\nLOCATION:\n MC 5501\n\nABSTRACT: The mirror of a smooth Fano to ric variety is a Laurent\npolynomial\, and this Laurent polynomial encodes interesting\nenumerative data of the toric variety.  For example\, the J acobian\nring of the Laurent polynomial is isomorphic to the small quantum \ncohomology ring of the toric variety. In this talk\, I’ll describe\nth is aspect of the (now basically classical) toric mirror theorem\, and\nexp lain how this picture is expected to extend to other smooth Fano\nvarietie s. The Grassmannian’s strong combinatorial structure  makes\nit one of the nicest examples of non-toric Fano varieties to study in\nthis context. I’ll present several mirror constructions for the\nGrassmannian that ea ch reflect a different perspective on its\ngeometry. Finally\, I’ll disc uss some extensions of these\nconstructions to generalizations of the Gras smannian.  DTSTAMP:20260918T220810Z END:VEVENT BEGIN:VEVENT UID:6aadb64ad6115 DTSTART;TZID=America/Toronto:20260917T143000 SEQUENCE:0 TRANSP:TRANSPARENT DTEND;TZID=America/Toronto:20260917T153000 URL:https://uwaterloo.ca/combinatorics-and-optimization/events/characters-r ook-monoid SUMMARY:Characters of the rook monoid CLASS:PUBLIC DESCRIPTION:SEMINAR: Algebraic and Enumerative Combinatorics Seminar\nDATE: Thursday\, September 17\, 2026\nTIME: 2:30 PM\nLOCATION: MC 5417\nSPEAKER : Mike Zabrocki\nAFFILIATION: York University\nTITLE: Characters of the ro ok monoid\nABSTRACT:\n\nThe partial permutations form a monoid known in di fferent contexts as\neither the “symmetric inverse semigroup” or the “rook monoid.”\nIn this talk I will define a family of symmetric funct ions that\nevaluate to the character values of the irreducible representat ions of\nthe monoid. The basis also connects to the representation theory of\nthe Schur-Weyl duality with the “propagating partition algebra.”\n Moreover\, the structure coefficients of this basis interpolate between\nt he Kronecker coefficients and the Littlewood-Richardson coefficients\nand we use it to develop some of the combinatorics of the connection.\n\nThis is joint work with Rosa Orellana and Alex Wilson.\n\nThere will be a pre-s eminar presenting relevant background at\nbeginning graduate level startin g at 1:30pm in MC 5417.\n\n  DTSTAMP:20260918T220810Z END:VEVENT BEGIN:VEVENT UID:6aadb64ad72d4 DTSTART;TZID=America/Toronto:20260911T153000 SEQUENCE:0 TRANSP:TRANSPARENT DTEND;TZID=America/Toronto:20260911T163000 URL:https://uwaterloo.ca/combinatorics-and-optimization/events/tutte-colloq uium-luke-postle-university-waterloo SUMMARY:Tutte Colloquium - Luke Postle\, University of Waterloo CLASS:PUBLIC DESCRIPTION:Title: A PROOF OF NASH-WILLIAMS’ CONJECTURE\n\nSpeaker: Luke Postle\n  \n\nAffiliation: University of Waterloo\n  \n\nLocation: MC 5 501\n  \n\nAbstract: A central open question in extremal design theory i s\nNash-Williams’ Conjecture from 1970\, namely that every\ntriangle-div isible graph on n vertices (for n large enough) with\nminimum degree at le ast 0.75n has a triangle decomposition. In this\ntalk\, we discuss the his tory of the problem and our recent resolution\nof this conjecture\, as wel l as other applications in design theory. We\nalso overview the proof\, hi ghlighting the new techniques we developed\nto resolve the fractional vers ion as well as the full conjecture.\nJoint work with Michelle Delcourt. DTSTAMP:20260918T220810Z END:VEVENT BEGIN:VEVENT UID:6aadb64ad8651 DTSTART;TZID=America/Toronto:20260908T130000 SEQUENCE:0 TRANSP:TRANSPARENT DTEND;TZID=America/Toronto:20260908T143000 URL:https://uwaterloo.ca/combinatorics-and-optimization/events/mike-cumming s-introduction-complexes-and-simplicial-homology SUMMARY:Mike Cummings-Introduction\, ∆-complexes\, and simplicial homolog y CLASS:PUBLIC DESCRIPTION:SPEAKER:\n Mike Cummings\n\nAFFILIATION:\n University of Waterl oo\n\nLOCATION:\n MC 6029\n\n-------------------------\n\nABSTRACT: This term we are running a learning seminar on homology and\ncohomology\, follo wing Chapters 2 and 3 of Hatcher.  In this first\nmeeting\, we will brief ly talk about our plans for the seminar\, and\nthen will jump right into s implicial homology. All are welcome! DTSTAMP:20260918T220810Z END:VEVENT BEGIN:VEVENT UID:6aadb64ad93db DTSTART;TZID=America/Toronto:20260811T140000 SEQUENCE:0 TRANSP:TRANSPARENT DTEND;TZID=America/Toronto:20260811T150000 URL:https://uwaterloo.ca/combinatorics-and-optimization/events/iqc-seminar- calvin-liu-recent-advances-random-quantum SUMMARY:IQC Seminar - Calvin Liu - Recent advances in random quantum circui t\nsampling CLASS:PUBLIC DESCRIPTION:SPEAKER:\n Calvin Liu\n\nAFFILIATION: \n University of Waterlo o\n\nLOCATION:\n MC 5029\n\nABSTRACT: \n\nIn 2019\, Google announced the demonstration of quantum supremacy by\nperforming a computational task kno wn as random circuit sampling on\ntheir 53-qubit quantum computer Sycamore . In their paper\, they claimed\nthat it would take classical computers 10 000 years to perform the same\ntask. Almost seven years has passed\, and w hat happened to this claim\nsince then? In this talk\, I will provide a hi gh-level update on the\nsubsequent developments in quantum hardware experi ments\, classical\nsimulation software\, asymptotic classical simulation a lgorithms\, and\nproving the hardness of classical simulation. This talk i s aimed at a\nnon-quantum computing audience\, and no prior background in quantum\ncomputing is assumed. DTSTAMP:20260918T220810Z END:VEVENT BEGIN:VEVENT UID:6aadb64ada19d DTSTART;TZID=America/Toronto:20260807T110000 SEQUENCE:0 TRANSP:TRANSPARENT DTEND;TZID=America/Toronto:20260807T120000 URL:https://uwaterloo.ca/combinatorics-and-optimization/events/masters-thes is-presentation-amaan-khan-study-first-order SUMMARY:Master's Thesis Presentation - Amaan Khan - A Study of First-Order\ nPrimal-Dual Algorithms for Linear Optimization CLASS:PUBLIC DESCRIPTION:SPEAKER: \n Amaan Khan\n\nSUPERVISOR:\n Levent Tuncel\n\nLOCAT ION: \n MC 5479\n\nABSTRACT: \n\nSecond-order Interior Point Methods (IP M) have been studied\nextensively over the past 80 years\, proving effecti ve for conic\noptimization. They can produce high-precision approximate so lutions in\nfew iterations. Each iteration is computationally expensive: T he core\nof each iteration is a large matrix inversion that scales poorly with\nthe number of variables.\n\nIn large-scale applications\, we cannot bear the per-iteration cost\n(perhaps due to lack of memory)\, so we inste ad turn to first-order\nmethods. We study a first-order IPM that uses a lo w-rank update scheme\nto replace the matrix inversion with significantly l ower per-iteration\ncost\, and compare this to other first-order methods f or solving LP at\nscale. DTSTAMP:20260918T220810Z END:VEVENT BEGIN:VEVENT UID:6aadb64adb4c2 DTSTART;TZID=America/Toronto:20260807T153000 SEQUENCE:0 TRANSP:TRANSPARENT DTEND;TZID=America/Toronto:20260807T163000 URL:https://uwaterloo.ca/combinatorics-and-optimization/events/tutte-colloq uium-michael-friedlander-measure-cone-randomness SUMMARY:Tutte Colloquium -Michael Friedlander-The Measure of a Cone:\nRando mness and exactness in convex optimization CLASS:PUBLIC DESCRIPTION:SPEAKER:\n Michael Friedlander\n\nAFFILIATION:\n University of British Columbia.\n\nLOCATION:\n MC 5501\n\nABSTRACT: Conic geometry enco des combinatorial properties of a convex\nprogram. Under a probabilistic model of the data\, these combinatorial\nproperties become random events. Their likelihood is the measure of a\ncone. We illustrate this view with a dual pair of questions. First\,\nhow much can a linear program be regu larized before its solution\nchanges? With random costs\, the answer turn s on the Gaussian measure\nof the solution's normal cone. Second\, how ma ny measurements are\nneeded to separate a superposition of structured sig nals? Here\, each\nsignal's complexity is the statistical dimension of its  descent cone.\nA convex program recovers the components once the measure ment count\nexceeds the total complexity.\n\nBased on joint work with Sha rvaj Kubal\, Yaniv Plan\, and Matthew Scott\;\nZhenan Fan\, Halyun Jeong\ , and Babhru Joshi\; and Ives Macêdo and Ting\nKei Pong. DTSTAMP:20260918T220810Z END:VEVENT BEGIN:VEVENT UID:6aadb64adc579 DTSTART;TZID=America/Toronto:20260810T140000 SEQUENCE:0 TRANSP:TRANSPARENT DTEND;TZID=America/Toronto:20260810T150000 URL:https://uwaterloo.ca/combinatorics-and-optimization/events/masters-thes is-presentation-david-evangelista-backedge SUMMARY:Master's Thesis Presentation - David Evangelista - Backedge Graphs of\nTournaments: Algorithms and Complexity CLASS:PUBLIC DESCRIPTION:SPEAKER:\n David Evangelista\n\nSUPERVISOR(S):\n Joseph Cheriya n and Sophie Spirkl\n\nCOMMITTEE:\n Jane Gao\, Eric Blais\n\nLOCATION:\n M C 5417\n\nABSTRACT: \n\nA tournament $\\T=(V\,A)$ on $n$ vertices is an o rientation of the\ncomplete graph $K_n$. The backedge graph of $T$ with re spect to an\nordering of $V$ is the undirected graph on vertex set $V$ who se edge\nset corresponds to the arcs directed from a later vertex to an ea rlier\nvertex in the ordering. Backedge graphs provide concise\nrepresenta tions of the tournament. The algorithmic problem of\ndetermining whether a tournament admits a backedge graph in a given\nclass of undirected graphs varies in complexity\, and is often\nequivalent to computing parameters o f tournaments\, such as\ndegreewidth when the backedge graph has bounded maximum degree\n\\cite{Davot et al.\, 2023}. We extend the notion of degre ewidth by\nintroducing directional degreewidth\, which separately bounds t he\nleft-degrees and right-degrees of vertices in addition to bounding the \ntotal degrees. We obtain an algorithm for verifying bounds on the\ndirec tional degreewidth of the tournament\, whose runtime is polynomial\ntime w hen the total degree is unbounded\, or fixed-parameter tractable\ntime wit h respect to the total degree bound otherwise. We also provide\na polynomi al-time algorithm for computing a $P_3$-free backedge graph\nof a tourname nt\, if it exists. Together with existing results\, the\nlatter result set tles the complexity of determining whether a\ntournament admits an $H$-fre e backedge graph when $H$ is any graph on\nthree vertices. DTSTAMP:20260918T220810Z END:VEVENT END:VCALENDAR