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:6ae9650d08f40 DTSTART;TZID=America/Toronto:20261002T153000 SEQUENCE:0 TRANSP:TRANSPARENT DTEND;TZID=America/Toronto:20261002T163000 URL:https://uwaterloo.ca/combinatorics-and-optimization/events/tutte-colloq uium-recent-progress-erdos-rogers-function SUMMARY:Tutte Colloquium | Recent Progress on Erdos-Rogers Function CLASS:PUBLIC DESCRIPTION:SPEAKER:\n Jacques Verstraete\n\nAFFILIATION:\n University of C alifornia\n\nLOCATION:\n MC 5501\n\nABSTRACT: For positive integers $s$ a nd $n$\, let $f_{s}(n)$ denote\nthe maximum $k$ such that every $n$-vertex $K_{s+1}$-free graph\ncontains an induced $K_s$-free subgraph with $k$ ve rtices. These are\nthe Erd\\H{o}s-Rogers functions\, introduced by Erd\\H{ o}s and Rogers in\n1962\, and are generalizations of Ramsey numbers.\n\nIn this talk we survey recent progress\, culminating with the recent\nresult of Morris\, Saharasbudhe which finally determines the order of\nmagnitude of the Erd\\H{o}s-Rogers functions.\n\nJoint work with Rob Morris and Jul ian Saharasbudhe. DTSTAMP:20261103T043733Z END:VEVENT BEGIN:VEVENT UID:6ae9650d0a238 DTSTART;TZID=America/Toronto:20260928T150000 SEQUENCE:0 TRANSP:TRANSPARENT DTEND;TZID=America/Toronto:20260928T160000 URL:https://uwaterloo.ca/combinatorics-and-optimization/events/graphs-and-m atroids-kaioke-begay-finitary-and-cofinitary SUMMARY:Graphs and Matroids | Kaioke Begay- Finitary and Cofinitary Oriente d\nMatroids CLASS:PUBLIC DESCRIPTION:SPEAKER:\n Kaioke Begay\n\nAFFILIATION:\n University of Waterlo o\n\nROOM:\n MC 6029\n\nABSTRACT: Much like matroids\, oriented matroids can be defined on\nfinite ground sets using a set of circuit axioms. Orien ted matroid\nduality is an important property which is difficult to mainta in in the\ninfinite setting. One way to define infinite oriented matroids in a\nway that preserves duality is using signed set orthogonality. This\n allows for the notion of finitary and cofinitary oriented matroids. An\nor iented matroid is called finitary if all of its circuits have finite\nsupp ort\, and cofinitary if it is the dual of a finitary oriented\nmatroid. It has recently been shown that cofinitary oriented matroids\ndo not necessa rily satisfy the circuit axioms. In the finite setting\,\nthere are many w ays to define oriented matroids which are equivalent\nto the circuit axiom s. Here\, we prove that some of these definitions\nstill hold for cofinita ry oriented matroids\, even when the circuit\naxioms fail. DTSTAMP:20261103T043733Z END:VEVENT BEGIN:VEVENT UID:6ae9650d0a9c5 DTSTART;TZID=America/Toronto:20260924T143000 SEQUENCE:0 TRANSP:TRANSPARENT DTEND;TZID=America/Toronto:20260924T153000 URL:https://uwaterloo.ca/combinatorics-and-optimization/events/algebraic-an d-enumerative-combinatorics-seminar-lizzie-pratt SUMMARY:Algebraic and Enumerative Combinatorics Seminar - Lizzie Pratt -\nO n-shell Forms and Hypertree Divisors CLASS:PUBLIC DESCRIPTION:SPEAKER:\n Lizzie Pratt\n\nAFFILIATION:\n Perimeter Institute\n \nLOCATION:\n MC 5417\n\nABSTRACT: On-shell forms are differential forms on the Grassmannian\nwhich arise in particle physics. They are defined usi ng bipartite\ngraphs with n distinguished boundary vertices. Mathematical\ ninvestigation of on-shell forms has largely focused on the case of\nplana r graphs\, where one can use tools developed by Postnikov in the\nstudy of the totally nonnegative Grassmannian. In this talk we develop\nthe mathem atics of nonplanar on-shell forms\, and explain how they\narise in physics and math. For certain forms on the Grassmannian\nGr(2\,n)\, we prove a de terminantal formula appearing in the physics\nliterature\, and give a conn ection to the hypertree divisors of\nCastravet and Tevelev.\n\nTHERE WILL BE A PRE-SEMINAR PRESENTING RELEVANT BACKGROUND AT THE\nBEGINNING GRADUAT E LEVEL STARTING AT 1:30PM. DTSTAMP:20261103T043733Z END:VEVENT BEGIN:VEVENT UID:6ae9650d0b169 DTSTART;TZID=America/Toronto:20260925T153000 SEQUENCE:0 TRANSP:TRANSPARENT DTEND;TZID=America/Toronto:20260925T163000 URL:https://uwaterloo.ca/combinatorics-and-optimization/events/tutte-colloq uium-generating-and-utilizing-various-types SUMMARY:Tutte Colloquium - Generating and utilizing various types of negati ve\ndependence 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:20261103T043733Z END:VEVENT BEGIN:VEVENT UID:6ae9650d0bdbf DTSTART;TZID=America/Toronto:20260923T100000 SEQUENCE:0 TRANSP:TRANSPARENT DTEND;TZID=America/Toronto:20260923T110000 URL:https://uwaterloo.ca/combinatorics-and-optimization/events/crypto-readi ng-group-quantum-computing-introduction-quantum SUMMARY:Crypto Reading Group on quantum computing - Introduction to Quantum \nComputing CLASS:PUBLIC DESCRIPTION:For this term's reading group we will be hosting a study group on\nquantum tools in cryptography. For the first week\, we start with a\nm otivation on quantum computing including the basic definitions and\ndiscus sion on complexity classes. This will serve as a elementary\nfoundation fo r the rest of the reading group. A week-by-week plan\noutline [https://ww w.leonardocolo.com/seminars/Fall26.html]. DTSTAMP:20261103T043733Z END:VEVENT BEGIN:VEVENT UID:6ae9650d0c40a DTSTART;TZID=America/Toronto:20260918T153000 SEQUENCE:0 TRANSP:TRANSPARENT DTEND;TZID=America/Toronto:20260918T163000 URL:https://uwaterloo.ca/combinatorics-and-optimization/events/tutte-colloq uium-many-mirrors-grassmannian-and-beyond SUMMARY:Tutte Colloquium - 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:20261103T043733Z END:VEVENT BEGIN:VEVENT UID:6ae9650d0cfd4 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:20261103T043733Z END:VEVENT BEGIN:VEVENT UID:6ae9650d0dbbf 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:20261103T043733Z END:VEVENT BEGIN:VEVENT UID:6ae9650d0e224 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:20261103T043733Z END:VEVENT BEGIN:VEVENT UID:6ae9650d0e893 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:20261103T043733Z END:VEVENT END:VCALENDAR