BEGIN:VCALENDAR VERSION:2.0 PRODID:researchseminars.org CALSCALE:GREGORIAN X-WR-CALNAME:researchseminars.org BEGIN:VEVENT SUMMARY:Matthew Kennedy (University of Waterloo) DTSTART:20201002T213000Z DTEND:20201002T223000Z DTSTAMP:20260404T085114Z UID:ReginaMathColloquium/1 DESCRIPTION:Title: Operator algebras and group theory\nby Matthew Kennedy (U niversity of Waterloo) as part of University of Regina math & stats colloq uium\n\n\nAbstract\nSince the work of von Neumann\, the theory of operator algebras has been closely linked to the theory of groups. On the one hand \, operator algebras constructed from groups provide an important source o f examples and insight. On the other hand\, many problems about groups are most naturally studied within an operator-algebraic framework. In this ta lk I will introduce these ideas and discuss recent developments relating t he structure of a group to the structure of a corresponding operator algeb ra.\n LOCATION:https://researchseminars.org/talk/ReginaMathColloquium/1/ END:VEVENT BEGIN:VEVENT SUMMARY:Daniel Davis (University of Louisiana at Lafayette) DTSTART:20201023T213000Z DTEND:20201023T223000Z DTSTAMP:20260404T085114Z UID:ReginaMathColloquium/2 DESCRIPTION:Title: Lifting trivial actions from group cohomology to spectra\, fo r profinite groups\nby Daniel Davis (University of Louisiana at Lafaye tte) as part of University of Regina math & stats colloquium\n\n\nAbstract \nLet $G$ be a topological group that is compact\, Hausdorff\, and totally disconnected (such a group is "profinite")\, and let $A$ be any abelian g roup. Then $A$ can be regarded as a $G$-module by letting $G$ act triviall y on $A$\, and it is a known result that the continuous group cohomology o f $G$ with coefficients in $A$ can be obtained by taking a "union" of the ordinary group cohomology of certain finite quotient groups of $G$ with th e same coefficients.\n\nIn this talk\, we consider what happens when $A$ i s replaced by any spectrum (in the sense of homotopy theory)\, and group c ohomology\, which in degree $0$ is just the fixed points of the group acti on\, is replaced with homotopy fixed points. We give some conditions that guarantee that in this new setting\, there is an analogue of the aforement ioned "known result".\n LOCATION:https://researchseminars.org/talk/ReginaMathColloquium/2/ END:VEVENT BEGIN:VEVENT SUMMARY:Michael Brannan (Texas A&M University) DTSTART:20201030T213000Z DTEND:20201030T223000Z DTSTAMP:20260404T085114Z UID:ReginaMathColloquium/3 DESCRIPTION:Title: Quantum graphs and quantum Cuntz-Krieger algebras\nby Mic hael Brannan (Texas A&M University) as part of University of Regina math & stats colloquium\n\n\nAbstract\nIn this talk I will give a light introduc tion to the theory of quantum graphs. Quantum graphs are generalizations o f directed graphs within the framework of non-commutative geometry\, and t hey arise naturally in a surprising variety of areas including quantum inf ormation theory\, representation theory\, and in the theory of non-local g ames. I will give an overview of some of these connections and also explai n how one can generalize the well-known construction of Cuntz-Krieger $C^* $-algebras associated to ordinary graphs to the setting of quantum graphs. Time permitting\, I will also explain how quantum symmetries of quantum graphs can be used to shed some light on the structure of quantum Cuntz-Kr ieger algebras. (This is joint work with Kari Eifler\, Christian Voigt\, and Moritz Weber.)\n LOCATION:https://researchseminars.org/talk/ReginaMathColloquium/3/ END:VEVENT BEGIN:VEVENT SUMMARY:Andrei Volodin (University of Regina) DTSTART:20201127T213000Z DTEND:20201127T223000Z DTSTAMP:20260404T085114Z UID:ReginaMathColloquium/4 DESCRIPTION:Title: On the Golden Ratio\, Strong Law\, and First Passage Problem< /a>\nby Andrei Volodin (University of Regina) as part of University of Reg ina math & stats colloquium\n\n\nAbstract\nFor a sequence of correlated sq uare integrable random variables $\\{X_n\, n\\geq 1\\}$\, conditions are p rovided for the strong law of large numbers\n\\[\n\\lim_{n\\to \\infty} \\ frac{S_{n}- ES_{n} }{ n }=0\n\\]\nalmost surely to hold\, where $\\ S_{n}= \\sum^n_{i=1}{X_{i}}$. The hypotheses stipulate that two series converge\, the terms of which involve\, respectively\, both the Golden Ratio $\\varp hi=\\frac{1 + \\sqrt{5}}{2}$ and bounds on Var $X_n$ (respectively\, bound s on Cov $(X_n\, X_{n+m}))$. An application to first passage times is pro vided.\n LOCATION:https://researchseminars.org/talk/ReginaMathColloquium/4/ END:VEVENT BEGIN:VEVENT SUMMARY:Anna Marie Bohmann (Vanderbilt University) DTSTART:20210122T213000Z DTEND:20210122T223000Z DTSTAMP:20260404T085114Z UID:ReginaMathColloquium/5 DESCRIPTION:Title: Detecting algebraic structures: K-theory and Lawvere theories \nby Anna Marie Bohmann (Vanderbilt University) as part of University of Regina math & stats colloquium\n\n\nAbstract\nIn the 1950s and 60s\, ma thematicians began constructing the invariants of rings that are called "$ K$-theory." The $K$-theory of rings is hard to compute\, but it contains lots of interesting information about algebra\, number theory\, and topolo gy. For example\, $K$-theory detects when rings are "the same" in the sen se of having suitably equivalent categories of modules\, which is called M orita invariance. In this talk\, I will discuss the $K$-theory of rings a s well as new work with Markus Szymik about the $K$-theory of a more gener al kind of algebraic structure\, called a Lawvere theory. In the latter c ase\, we show that while the $K$-theory of Lawvere theories contains lots of interesting information\, it fails to satisfy Morita invariance!\n LOCATION:https://researchseminars.org/talk/ReginaMathColloquium/5/ END:VEVENT BEGIN:VEVENT SUMMARY:Jason Crann (Carleton University) DTSTART:20210129T213000Z DTEND:20210129T223000Z DTSTAMP:20260404T085114Z UID:ReginaMathColloquium/6 DESCRIPTION:Title: Amenable dynamical systems through Herz--Schur multipliers\nby Jason Crann (Carleton University) as part of University of Regina ma th & stats colloquium\n\n\nAbstract\nThe Herz--Schur multiplier manifestat ion of amenability provides a fundamental link between abstract harmonic a nalysis and operator algebras\, allowing for a fruitful exchange of ideas and tools between the two areas. A generalized theory of Herz--Schur multi pliers for dynamical systems has recently emerged through independent work of Bedos--Conti and McKee--Todorov--Turowska.\n\nIn this talk\, we genera lize the aforementioned link by establishing Herz--Schur multiplier charac terizations of amenable $W^*$- and $C^*$-dynamical systems over arbitrary locally compact groups. As byproducts of our results\, we (1) answer a que stion of Anantharaman-Delaroche and obtain a Reiter type characterization of amenable $W^*$-dynamical systems\, and (2) show that a commutative $C^* $-dynamical system $(C_0(X)\,G\,\\alpha)$ is amenable if and only if the a ction of $G$ on $X$ is topologically amenable. Combined with recent work o f Buss--Echterhoff--Willett\, this latter result implies the equivalence b etween topological amenability and measurewise amenabilty for $G$-spaces $ X$ when both $G$ and $X$ are second countable. This is joint work with Ale x Bearden.\n LOCATION:https://researchseminars.org/talk/ReginaMathColloquium/6/ END:VEVENT BEGIN:VEVENT SUMMARY:Seyed Ahmad Mojallal (University of Regina) DTSTART:20210305T213000Z DTEND:20210305T223000Z DTSTAMP:20260404T085114Z UID:ReginaMathColloquium/7 DESCRIPTION:Title: Applications of the vertex-clique incidence matrix of a graph \nby Seyed Ahmad Mojallal (University of Regina) as part of University of Regina math & stats colloquium\n\n\nAbstract\nIn this talk\, we make u se of an interaction between the theory of clique partitions of a graph an d graph spectra. We use the theory of clique partitions and introduce the notion of a vertex-clique incidence matrix of the graph. We give new lower bounds for the negative eigenvalues and negative inertia of a graph. More over\, utilizing vertex-clique incidence matrices\, we generalize several notions such as the signless Laplacian matrix and a line graph of a graph as well as the incidence energy and the signless Laplacian energy of the g raph.\n\nApplying a similar type of incidence matrices obtained from the t heory of clique covering\, we report on some recent research studying the minimum number of distinct eigenvalues of a graph.\n\nThis is joint work w ith Shaun Fallat.\n LOCATION:https://researchseminars.org/talk/ReginaMathColloquium/7/ END:VEVENT BEGIN:VEVENT SUMMARY:David Sherman (University of Virginia) DTSTART:20210319T213000Z DTEND:20210319T223000Z DTSTAMP:20260404T085114Z UID:ReginaMathColloquium/8 DESCRIPTION:Title: Model theory for functional analysis\nby David Sherman (U niversity of Virginia) as part of University of Regina math & stats colloq uium\n\n\nAbstract\nModel theory studies the interplay between mathematica l structures and their logical properties. Some of its most beautiful the orems involve a construction called an ultrapower. Many standard objects in functional analysis\, such as Banach spaces and operator algebras\, car ry useful notions of ultrapower\, but this does not interact well with cla ssical model theory. An elegant solution\, very natural for analysts\, is to switch to a logic in which truth values are drawn from the interval $[ 0\,1]$. I will give a "big picture" survey of this approach and its prehi story\, not assuming that the audience has any familiarity with logic or u ltrapowers.\n LOCATION:https://researchseminars.org/talk/ReginaMathColloquium/8/ END:VEVENT BEGIN:VEVENT SUMMARY:Ilijas Farah (York University) DTSTART:20210910T213000Z DTEND:20210910T223000Z DTSTAMP:20260404T085114Z UID:ReginaMathColloquium/9 DESCRIPTION:Title: Coarse geometry and rigidity\nby Ilijas Farah (York Unive rsity) as part of University of Regina math & stats colloquium\n\n\nAbstra ct\nCoarse geometry is the study of metric spaces when one forgets about t he small scale structure and focuses only on the large scale. For example\ , this philosophy underlies much of geometric group theory. To a coarse s pace one associates an algebra of operators on a Hilbert space\, called th e uniform Roe algebra. No familiarity with coarse geometry\, operator alg ebras\, or logic is required. After introducing the basics of coarse spac es and uniform Roe algebras\, we will consider the following rigidity ques tions:\n\n(1) If the uniform Roe algebras associated to coarse spaces X an d Y are isomorphic\, when can we conclude that X and Y are coarsely equiva lent?\n\n(2) The uniform Roe corona is obtained by modding out the compact operators. If the uniform Roe coronas of X and Y are isomorphic\, what ca n we conclude about the relation between the underlying uniform Roe algebr as (or about the relation between X and Y)? \n\nThe answers to these quest ions are fairly surprising. This talk is based on a joint work with F. Bau dier\, B.M. Braga\, A. Khukhro\, A. Vignati\, and R. Willett.\n LOCATION:https://researchseminars.org/talk/ReginaMathColloquium/9/ END:VEVENT BEGIN:VEVENT SUMMARY:Maria Gillespie (Colorado State University) DTSTART:20211001T213000Z DTEND:20211001T223000Z DTSTAMP:20260404T085114Z UID:ReginaMathColloquium/10 DESCRIPTION:Title: Tournaments and the geometry of curves\nby Maria Gillesp ie (Colorado State University) as part of University of Regina math & stat s colloquium\n\n\nAbstract\nHow many lines pass through four given fixed l ines in three dimensional space? How many cubic curves in three dimension s pass through 5 given points and are also tangent to two fixed planes? \ n\nThe first question is a classical problem of "Schubert calculus"\, and can be solved via a simple count of combinatorial objects called Young tab leaux. The second can be approached using intersection theory on moduli s paces of curves\, and in this talk we present new combinatorial methods vi a algorithms on labeled trees called "tournaments" that enable us to more easily solve enumerative problems about curves. These results are due to joint work with Sean Griffin and Jake Levinson.\n LOCATION:https://researchseminars.org/talk/ReginaMathColloquium/10/ END:VEVENT BEGIN:VEVENT SUMMARY:Nicholas Scoville (Ursinus College) DTSTART:20211203T213000Z DTEND:20211203T223000Z DTSTAMP:20260404T085114Z UID:ReginaMathColloquium/11 DESCRIPTION:Title: Towards a new digital homotopy theory\nby Nicholas Scovi lle (Ursinus College) as part of University of Regina math & stats colloqu ium\n\n\nAbstract\nWe present recent progress with collaborators Greg Lupt on and John Oprea towards developing a digital version of homotopy theory. An $n$-dimensional digital image is a finite subset of the integer latti ce along with an adjacency relation. Although there are many papers on di gital homotopy theory\, many of the notions do not seem satisfactory from a homotopy point of view. Indeed\, some of the constructs most useful in homotopy theory\, such as cofibrations and path spaces\, are absent from the literature or completely trivial.\n\nWorking in the digital setting\, we develop some basic ideas of homotopy theory\, including cofibrations an d path fibrations\, in a way that seems more suited to homotopy theory. W e will indicate how our approach may be used\, for example\, to study Lust ernik-Schnirelmann category in a digital setting. One future goal is to d evelop a characterization of a "homotopy circle" (in the digital setting) using the notion of topological complexity. This is with a view towards r ecognizing circles\, and perhaps other features\, using these ideas. This talk will introduce some of the basics of digital topology and will not r equire any specialized background.\n LOCATION:https://researchseminars.org/talk/ReginaMathColloquium/11/ END:VEVENT BEGIN:VEVENT SUMMARY:Jesse Peterson (Vanderbilt University) DTSTART:20220204T213000Z DTEND:20220204T223000Z DTSTAMP:20260404T085114Z UID:ReginaMathColloquium/12 DESCRIPTION:Title: Character Rigidity in Higher-Rank Groups\nby Jesse Peter son (Vanderbilt University) as part of University of Regina math & stats c olloquium\n\n\nAbstract\nA character on a group is a class function of pos itive type. For finite groups\, the classification of characters is closel y related to the representation theory of the group and plays a key role i n the classification of finite simple groups. Based on the rigidity result s of Mostow\, Margulis\, and Zimmer\, it was conjectured by Connes that fo r lattices in higher rank simple Lie groups\, the space of characters shou ld be completely determined by their finite dimensional representations. I n this talk\, I will discuss the solution to this conjecture\, as well as a recent remarkable extension by Boutonnet and Houdayer. I will also discu ss the relationship to ergodic theory\, invariant random subgroups\, and v on Neumann algebras.\n LOCATION:https://researchseminars.org/talk/ReginaMathColloquium/12/ END:VEVENT BEGIN:VEVENT SUMMARY:Benjamin Steinberg (City College of New York) DTSTART:20220218T213000Z DTEND:20220218T223000Z DTSTAMP:20260404T085114Z UID:ReginaMathColloquium/13 DESCRIPTION:Title: Factoring the Dedekind-Frobenius determinant\nby Benjami n Steinberg (City College of New York) as part of University of Regina mat h & stats colloquium\n\n\nAbstract\nIn 1875\, Smith computed the determina nt of the $n \\times n$ matrix whose $(i\,j)$-entry is $\\gcd(i\,j)$. This matrix is nothing other than the multiplication table of the semigroup $\ \{ 1\, \\ldots\, n \\}$ under the binary operation of gcd. Dedekind introd uced in 1896\, in correspondence with Frobenius\, the group determinant of a finite group\, which is the formal determinant of the multiplication ta ble of the group. His motivation came from trying to compute the discrimin ant of a finite Galois extension of $\\mathbb{Q}$. Frobenius famously inve nted the representation theory of finite groups precisely to factor Dedeki nd's group determinant. Studying a generalization of the group determinant also led Frobenius to characterizing the algebras nowadays called Frobeni us algebras.\n\nOf course\, there is no reason to only compute the determi nant of a group multiplication table. People have looked at both semigroup s and Latin squares. Generalizing the work of Smith mentioned earlier\, Li ndstrom and Wilf independently published papers in 1967 computing the semi group determinant of a meet semilattice. For Wilf\, the primary motivation was to compute determinants of various matrices arising from combinatoria l objects and his paper\, entitled "Hadamard determinants\, Mobius functio ns\, and the chromatic number of a graph"\, was published in the Bulletin of the AMS.\n\nIn 1998\, Jay Wood\, who works in Coding theory\, factored the determinant of the multiplicative semigroup of a finite commutative ch ain ring\; these are rings whose ideals form a chain like $\\mathbb{Z}/p^n \\mathbb{Z}$ with $p$ a prime. His motivation was to prove a generalizati on of the MacWilliams extension theorem for codes over a finite field to c odes over a finite ring. This theorem says that a partial isometry between codes can be extended to a global isometry with respect to the Hamming me tric. Eventually\, it was shown using methods unrelated to semigroup deter minants that the MacWilliams extension theorem holds precisely for finite Frobenius rings.\n\nIn this talk\, I'll survey some results I've obtained in a more systematic attempt to factor the semigroup determinant. The semi group determinant is a special case of Frobenius's paratrophic determinant of an algebra and so the semigroup determinant is nonzero if and only if the semigroup algebra is Frobenius. Our main results are a factorization o f the determinant of an inverse semigroup (generalizing simultaneously Fro benius and the Lindstrom-Wilf theorem) and a factorization of the semigrou p determinant of a commutative semigroup. Our final result says that the s emigroup algebra of a finite Frobenius ring is a Frobenius algebra. This i mplies as a special case the celebrated result of Okninski and Putcha that every complex representation of the multiplicative semigroup of $n \\time s n$ matrices over a finite field is completely reducible. It also suggest s that the MacWilliams extension theorem for finite Frobenius rings should be provable using the semigroup determinant method.\n LOCATION:https://researchseminars.org/talk/ReginaMathColloquium/13/ END:VEVENT BEGIN:VEVENT SUMMARY:Vesna Stojanoska (University of Illinois at Urbana-Champaign) DTSTART:20220318T213000Z DTEND:20220318T223000Z DTSTAMP:20260404T085114Z UID:ReginaMathColloquium/14 DESCRIPTION:Title: Duality for some Galois groups in stable homotopy theory \nby Vesna Stojanoska (University of Illinois at Urbana-Champaign) as part of University of Regina math & stats colloquium\n\n\nAbstract\nIn classic al algebra\, the integer primes $p$ help decompose objects as well as prob lems into their $p$-primary parts\, which may be easier to study. The same is true in homotopy theory\, but the situation is more interesting since for each integer prime $p$\, there are infinitely many nested homotopical primes. For each of those homotopical primes\, there is an (unramified) Ga lois group that governs the local story and encodes the symmetries of chro matic homotopy theory. These Galois groups turn out to be particularly nic e profinite groups\, known as compact $p$-adic analytic. Such groups and t heir fascinating duality properties within algebra were studied by Lazard. I will try to explain a newer result\, which shows that their homotopical duality properties are even better\, giving powerful implications for the chromatic Galois extensions that they govern.\n LOCATION:https://researchseminars.org/talk/ReginaMathColloquium/14/ END:VEVENT BEGIN:VEVENT SUMMARY:Ada Chan (York University) DTSTART:20220401T213000Z DTEND:20220401T223000Z DTSTAMP:20260404T085114Z UID:ReginaMathColloquium/15 DESCRIPTION:Title: State transfer in complex quantum walks\nby Ada Chan (Yo rk University) as part of University of Regina math & stats colloquium\n\n \nAbstract\nThe continuous-time quantum walk on a finite graph $X$ is defi ned by the time-dependent unitary matrix \n\\[\nU(t) = e^{itH}\,\n\\]\nwhe re the Hamiltonian $H$ is some Hermitian matrix associated with $X$. Per fect state transfer from vertex $a$ to vertex $b$ occurs if $U(t)_{b\,a}$ has unit magnitude at some time $t$. This phenomenon is relevant for infor mation transmission in quantum spin networks. Most previous studies on per fect state transfer used the adjacency matrix or the Laplacian matrix of $X$ as the Hamiltonian. \n\nIn this talk\, we focus on continuous-time q uantum walks with complex Hamiltonian. We examine how state transfer with complex Hamiltonian behaves differently from the quantum walks whose Hami ltonian is the adjacency matrix or the Laplacian matrix of a graph.\n\nThi s is joint work with Chris Godsil\, Christino Tamon\, Xiaohong Zhang\, and Fields undergraduate summer research students Antonio Acuaviva\, Summer E lridge\, Matthew How and Emily Wright.\n LOCATION:https://researchseminars.org/talk/ReginaMathColloquium/15/ END:VEVENT BEGIN:VEVENT SUMMARY:Ferdinand Ihringer (Ghent University) DTSTART:20220603T213000Z DTEND:20220603T223000Z DTSTAMP:20260404T085114Z UID:ReginaMathColloquium/16 DESCRIPTION:Title: Caps and Probabilistic Methods\nby Ferdinand Ihringer (G hent University) as part of University of Regina math & stats colloquium\n \nLecture held in RI 208 (Research and Innovation Centre).\n\nAbstract\nA set of points in a finite projective space $\\mathrm{PG}(n\, q)$ with no t hree collinear is called a cap. More generally\, a set of points in $\\mathrm{PG}(n\, q)$ such that no $s$-space contains more than $r$ point s is called an $(r\, s\; n\, q)$-set. In the first (and main) part of the talk we will discuss probabilisitic approaches to this classical problem.\ n\nIn the second part of the talk\, if time permits\, we will discuss one reason why it is so hard to construct large caps. For this we present para meter restrictions on approximately strongly regular graphs. This i s joint work with Jacques Verstraëte.\n LOCATION:https://researchseminars.org/talk/ReginaMathColloquium/16/ END:VEVENT BEGIN:VEVENT SUMMARY:Inna Zakharevich (Cornell University) DTSTART:20221007T213000Z DTEND:20221007T223000Z DTSTAMP:20260404T085114Z UID:ReginaMathColloquium/17 DESCRIPTION:Title: Point counting with twists\nby Inna Zakharevich (Cornell University) as part of University of Regina math & stats colloquium\n\n\n Abstract\nConsider a variety over a finite field. The number of points ove r the field is not only an invariant of the variety\, but also of its "sci ssors congruence" type: of we cut up the variety into locally closed piece s\, and rearrange those pieces into another variety\, the number of points does not change. Moreover\, if we have an automorphism of a variety\, the permutation induced on the points is similarly an invariant of the automo rphism. In this talk we will discuss a way of enhancing this invariant to an invariant which can distinguish different types of automorphisms and us e it to detect some interesting structures in the higher $K$-theory groups of varieties.\n LOCATION:https://researchseminars.org/talk/ReginaMathColloquium/17/ END:VEVENT BEGIN:VEVENT SUMMARY:Daniel Soskin (University of Notre Dame) DTSTART:20230113T213000Z DTEND:20230113T223000Z DTSTAMP:20260404T085114Z UID:ReginaMathColloquium/18 DESCRIPTION:Title: Determinantal inequalities for totally positive matrices \nby Daniel Soskin (University of Notre Dame) as part of University of Reg ina math & stats colloquium\n\n\nAbstract\nTotally positive matrices are m atrices in which each minor is positive. Lusztig extended the notion to re ductive Lie groups. He also proved that specialization of elements of the dual canonical basis in representation theory of quantum groups at $q=1$ a re totally non-negative polynomials. Thus\, it is important to investigate classes of functions on matrices that are positive on totally positive ma trices. I will discuss two sources of such functions. One has to do with m ultiplicative determinantal inequalities (joint work with M. Gekhtman). An other deals with majorizing monotonicity of symmetrized Fischer's products which are known for hermitian positive semidefinite case which brings add itional motivation to verify if they hold for totally positive matrices as well (joint work with M. Skandera). The main tools we employed are networ k parametrization\, Temperley-Lieb and monomial trace immanants.\n LOCATION:https://researchseminars.org/talk/ReginaMathColloquium/18/ END:VEVENT BEGIN:VEVENT SUMMARY:Colin Ingalls (Carleton University) DTSTART:20230317T213000Z DTEND:20230317T223000Z DTSTAMP:20260404T085114Z UID:ReginaMathColloquium/19 DESCRIPTION:Title: Groupoids (Stacks) associated with non-commutative surfaces< /a>\nby Colin Ingalls (Carleton University) as part of University of Regin a math & stats colloquium\n\n\nAbstract\nThis is joint work with Eleonore Faber\, Matthew Satriano\, and Shinnosuke Okawa. This will be a general au dience talk. One of the main constructions of Connes' noncommutative geome try is a construction of the convolution algebra of a groupoid. It is not clear how to characterize which algebras can be obtained this way. We cons truct a groupoid associated to a smooth\, finite over its centre\, noncomm utative surface which has the same category of modules. This was done loca lly by Reiten and Van den bergh and in dimension one by Chan and I. We hop e to use this result to study Artin's conjectured classification of noncom mutative surfaces by reduction to characteristic $p$.\n LOCATION:https://researchseminars.org/talk/ReginaMathColloquium/19/ END:VEVENT END:VCALENDAR