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:6a21b64294d1a DTSTART;TZID=America/Toronto:20260603T153000 SEQUENCE:0 TRANSP:TRANSPARENT DTEND;TZID=America/Toronto:20260603T163000 URL:https://uwaterloo.ca/pure-mathematics/events/geometry-and-topology-semi nar-50 SUMMARY:Geometry and Topology Seminar CLASS:PUBLIC DESCRIPTION:RAGINI SINGHAL\, UNIVERSITY OF MÜNSTER\n\n_Solutions and sing ularities of the Ricci-harmonic flow and Ricci-like\nflows of G2-structure s_\n\nWe find explicit solutions and singularities of the Ricci-harmonic\n flow of $G_2$-structures on 7-dimensionalcontact Calabi-Yau manifolds\nand the 7-dimensional Heisenberg group. We prove that the natural\nco-closed$ G_2$-structure on a contact Calabi-Yau manifold as the\ninitial condition leads to an ancient solution of the Ricci-harmonic\nflow with a finite tim e Type I singularity. These are the first\nexamples of Type I singularitie s of the Ricci-harmonic flow. We also\nobtain similar (but different) resu lts for the Ricci-like flows of\n$G_2$-structures studied by Gianniotis--Z acharopoulos in\narXiv:2505.06872 (J. Geom. Anal. 36.2 (2026)) and of the negative\ngradient flow of an energy functional of $G_2$-structures studie d by\nWeiss--Witt. The talk is based on a joint work with Shubham Dwivedi\ n(Hamburg).\n\nMC 5417 DTSTAMP:20260604T173042Z END:VEVENT BEGIN:VEVENT UID:6a21b64298b77 DTSTART;TZID=America/Toronto:20260603T140000 SEQUENCE:0 TRANSP:TRANSPARENT DTEND;TZID=America/Toronto:20260603T150000 URL:https://uwaterloo.ca/pure-mathematics/events/geometry-and-topology-semi nar-49 SUMMARY:Geometry and Topology Seminar CLASS:PUBLIC DESCRIPTION:IZAR ALONSO\, RUTGERS UNIVERSITY\n\n_Gauge Theory on hyperkähl er manifolds_\n\n$H$-instantons are a distinguished type of connections on Riemannian\n$n$-manifolds\, as they are generalizations of anti-self-dual \nconnections to manifolds of dimensions greater than 4. Examples of\n$H$- instantons include primitive Hermitian Yang--Mills (pHYM)\nconnections\, $ \\mathrm{Spin}(7)$-instantons\,which have been of great\ninterest in the r ecent years\, and the less studied\n$\\mathrm{Sp}(n)$-instantons. In this talk\, I will describe\n$\\mathrm{Sp}(2)$-instantons on hyperk\\\"ahler $8 $-manifolds and their\nrelations with other gauge-theoretical objects. I w ill then describe\nthe construction of examples of $\\mathrm{Sp}(2)$-insta ntons\,pHYM\nconnections\, and $\\mathrm{Spin}(7)$-instantons with symmetr y on the\nmanifold $T^* \\mathbb{CP}^2$with the Calabi hyperk\\\"ahler str ucture.\nThis talk is based on arXiv:2508.17119.\n\nMC 5417 DTSTAMP:20260604T173042Z END:VEVENT BEGIN:VEVENT UID:6a21b64299b7d DTSTART;TZID=America/Toronto:20260605T113000 SEQUENCE:0 TRANSP:TRANSPARENT DTEND;TZID=America/Toronto:20260605T123000 URL:https://uwaterloo.ca/pure-mathematics/events/ergodic-theory-learning-se minar-2 SUMMARY:Ergodic Theory Learning Seminar CLASS:PUBLIC DESCRIPTION:JULIUS FRIZZELL\, UNIVERSITY OF WATERLOO\n\n_Mutliple recurrenc e for weakly-mixing transformations (Part II)_\n\nWe will continue to disc uss weakly-mixing transformations and work\ntowards proving a special case of the multiple recurrence theorem.\n\nMC 5417 DTSTAMP:20260604T173042Z END:VEVENT BEGIN:VEVENT UID:6a21b6429a803 DTSTART;TZID=America/Toronto:20260604T133000 SEQUENCE:0 TRANSP:TRANSPARENT DTEND;TZID=America/Toronto:20260604T150000 URL:https://uwaterloo.ca/pure-mathematics/events/computability-learning-sem inar-171 SUMMARY:Computability Learning Seminar CLASS:PUBLIC DESCRIPTION:JOEY LAKERDAS-GAYLE\, UNIVERSITY OF WATERLOO\n\n_Priority Argum ents on Trees_\n\nWe will introduce terminology for priority trees followi ng Steffen\nLempp's notes and compare the classicalpriority argument for S acks\nCone Avoidance Theorem with a proof that uses a priority tree.\n\nMC 5403 DTSTAMP:20260604T173042Z END:VEVENT BEGIN:VEVENT UID:6a21b6429b1aa DTSTART;TZID=America/Toronto:20260604T160000 SEQUENCE:0 TRANSP:TRANSPARENT DTEND;TZID=America/Toronto:20260604T170000 URL:https://uwaterloo.ca/pure-mathematics/events/quantum-mathematics-cataly st-seminar SUMMARY:Quantum Mathematics Catalyst Seminar CLASS:PUBLIC DESCRIPTION:ADINA GOLDBERG\, MITTAG-LEFFLER INSTITUTE\n\n_Quantum games and quantum graphs via the double category of quantum\nrelations_\n\nBinary r elations are ubiquitous. Classical nonlocal games (Bell\nscenarios) can be thought of as binary relations between question\npairs and answer pairs. Classical undirected graphs can be thought of\nas symmetric binary relatio ns on a vertex set. There is a notion of\nquantum relation: a quantum anal ogue of binary relation. Just as\nrelations can be transformed by function s\, quantum relations can be\ntransformed by quantum functions. The intera ctions between quantum\nrelations and quantum functions are made precise b y the double\ncategory of quantum sets\, quantum functions\, and quantum r elations. We\ndefine this new double category building on the work of Weav er\,\nKornell\, and Musto-Reutter-Verdon. We illustrate how the category\n suggests\, distinguishes\, and motivates quantizations of some\nconstructi ons/results from classical graph theory and nonlocal games.\nBasicterms re lated to C*-algebras\, bimodules\, and category theory will\ncome up\, but the talk can also be followed by analogy to the classical\nsetting.\n\nQN C 1201 DTSTAMP:20260604T173042Z END:VEVENT BEGIN:VEVENT UID:6a21b6429bc31 DTSTART;TZID=America/Toronto:20260527T153000 SEQUENCE:0 TRANSP:TRANSPARENT DTEND;TZID=America/Toronto:20260527T170000 URL:https://uwaterloo.ca/pure-mathematics/events/differential-geometry-work ing-seminar-191 SUMMARY:Differential Geometry Working Seminar CLASS:PUBLIC DESCRIPTION:VIKTOR MAJEWSKI\, UNIVERSITY OF WATERLOO\n\n_Obstructions to Sm ooth Full Holonomy Cayley Fibrations_\n\nWe study smooth fibrations of com pact torsion-free\n$\\textrm{Spin}(7)$-manifolds by Cayley submanifolds.Us ing geometric\nand topological constraints coming from the\n$\\textrm{Spin }(7)$-structure\, we show that only two topological\nconfigurations can ar ise. One of these is excluded by a spinnability\ncriterion for fiber bundl es\,with the relevant hypothesis verified\nusing gauge-theoretic input\, w hile the remaining case is reduced to an\nopen conjecture in $4$-manifold topology. In particular\, this rules\nout smooth Cayley fibrations on all known examples of compact\ntorsion-free $\\textrm{Spin}(7)$-manifolds.\n\n MC 5417 DTSTAMP:20260604T173042Z END:VEVENT BEGIN:VEVENT UID:6a21b6429c5f3 DTSTART;TZID=America/Toronto:20260529T113000 SEQUENCE:0 TRANSP:TRANSPARENT DTEND;TZID=America/Toronto:20260529T123000 URL:https://uwaterloo.ca/pure-mathematics/events/ergodic-theory-learning-se minar-1 SUMMARY:Ergodic Theory Learning Seminar CLASS:PUBLIC DESCRIPTION:JULIUS FRIZZELL\, UNIVERSITY OF WATERLOO\n\n_Multiple recurrenc e for weakly-mixing transformations._\n\nWe will cover some basic facts ab out weakly mixing transformations and\nwork towards proving a version of t he multiple recurrence theorem for\nmeasure-preserving systems with all of the transformations being\nweakly mixing.\n\nMC 5417 DTSTAMP:20260604T173042Z END:VEVENT BEGIN:VEVENT UID:6a21b6429d005 DTSTART;TZID=America/Toronto:20260528T110000 SEQUENCE:0 TRANSP:TRANSPARENT DTEND;TZID=America/Toronto:20260528T120000 URL:https://uwaterloo.ca/pure-mathematics/events/algebraic-geometry-working -seminar-101 SUMMARY:Algebraic Geometry Working Seminar CLASS:PUBLIC DESCRIPTION:ANNE JOHNSON\, UNIVERSITY OF WATERLOO\n\n_Twisted arcs on root stacks_\n\nWe briefly introduce the theory of stacks via the stack of tria ngles\nusing Kai Behrend’s exposition as a guide. We move on to Yasuda ’s\nnotion of the twisted arc space of a DM stack. As time permits\, we\ ntake up the special case of twisted arcs on a root stack.\n\nMC 5403 DTSTAMP:20260604T173042Z END:VEVENT BEGIN:VEVENT UID:6a21b6429dabf DTSTART;TZID=America/Toronto:20260528T133000 SEQUENCE:0 TRANSP:TRANSPARENT DTEND;TZID=America/Toronto:20260528T150000 URL:https://uwaterloo.ca/pure-mathematics/events/computability-learning-sem inar-170 SUMMARY:Computability Learning Seminar CLASS:PUBLIC DESCRIPTION:BARBARA CSIMA\, UNIVERSITY OF WATERLOO\n\n_Priority Arguments i n Computability Theory_\n\nThis term\, Computability Learning Seminar will focus on Priority\nArguments. Priority Arguments are a common proof techn ique used in\nComputability Theory. A theorem is broken down to being equi valent to\na list of requirements. These requirements are given a priority order\,\nand a strategy is devised to meet all the requirements\, making use of\nthe priority order. In the early days of the subject\, a big quest ion\n(Post’s Problem -1944) was whether there were any non-computable\nc omputably enumerable (c.e.) sets that were not Turing equivalent to\nthe h alting set. The solution\, from Friedberg (1957) and Muchnik\n(1956)\, was to construct a pair of Turing incomparable c.e. sets\,\nusing a finite in jury priority argument. In this first talk\, we will\nbegin our examinatio n of priority arguments by going through the proof\nof this theorem\, intr oducing definitions and reviewing notions from\nComputability Theory as ne eded along the way.\n\nMC 5403 DTSTAMP:20260604T173042Z END:VEVENT BEGIN:VEVENT UID:6a21b6429e74b DTSTART;TZID=America/Toronto:20260527T140000 SEQUENCE:0 TRANSP:TRANSPARENT DTEND;TZID=America/Toronto:20260527T153000 URL:https://uwaterloo.ca/pure-mathematics/events/differential-geometry-work ing-seminar-190 SUMMARY:Differential Geometry Working Seminar CLASS:PUBLIC DESCRIPTION:SPENCER KELLY\, UNIVERSITY OF WATERLOO\n\n_Sobolev Spaces Over Compact Manifolds_\n\nThe space of smooth sections of a vector bundle over a manifold is an\ninfinite dimensional Fréchet Space\, and thus many of the tools used\nin finite-dimensional geometry are rendered useless on thi s space.\nHowever\, taking the completion of this space with respect to th e\nSobolev norm\, we obtain a Banach space. What's even better is that in\ nthe $L^2$ case we obtain a Hilbert space. In this talk we will walk\nthro ugh different constructions of the$L^2$-Sobolev spaces of sections\nof a v ector bundle over a compact manifold\, and discuss the Sobolev\nembedding theorem. We will also work through some of the properties of\ndifferential operators on this space and\, time permitting\, we will\nfinish with the Berger-Ebin decomposition for differential operators\nwith injective symbo l.\n\nMC 5417 DTSTAMP:20260604T173042Z END:VEVENT END:VCALENDAR