From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on inbox.vuxu.org X-Spam-Level: *** X-Spam-Status: No, score=3.5 required=5.0 tests=DATE_IN_PAST_24_48, LOCALPART_IN_SUBJECT,RDNS_NONE,TO_NAME_SUBJ_NO_RDNS autolearn=no autolearn_force=no version=3.4.4 Received: (qmail 11613 invoked from network); 7 Sep 2023 01:34:20 -0000 Received: from unknown (HELO smtp2.mta.ca) (198.164.44.75) by inbox.vuxu.org with ESMTPUTF8; 7 Sep 2023 01:34:20 -0000 Received: from rr.mta.ca ([198.164.44.159]:53364) by smtp2.mta.ca with esmtp (Exim 4.80) (envelope-from ) id 1qe3pf-0005hM-Iv; Wed, 06 Sep 2023 22:29:19 -0300 Received: from majordomo by rr.mta.ca with local (Exim 4.92.1) (envelope-from ) id 1qe3pH-0001Qt-Du for categories-list@rr.mta.ca; Wed, 06 Sep 2023 22:28:55 -0300 From: To: Subject: categories: The New York City Category Theory Seminar Fall 2023 line up of speakers. Date: Tue, 5 Sep 2023 18:15:30 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-2" Content-Transfer-Encoding: quoted-printable Precedence: bulk Reply-To: Message-Id: =20 The New York City Category Theory Seminar Department of Computer Science =20 Department of Mathematics =20 The Graduate Center of The City University of New York =20 THIS SEMESTER, SOME TALKS WILL BE IN-PERSON AND SOME WILL BE ON ZOOM.=20 Time: Wednesdays 07:00 PM Eastern Time (US and Canada)=20 IN-PERSON INFORMATION:=20 365 Fifth Avenue (at 34th Street) map (Diagonally across from the Empire State Building)=20 New York, NY 10016-4309=20 Room 6417=20 The videos of the lectures will be put up on YouTube a few hours after = the lecture.=20 ZOOM INFORMATION:=20 https://brooklyn-cuny-edu.zoom.us/j/83243451066?pwd=3DV3BkMCtxTnM3WTQ0QlN= 3K3NR RHNSQT09=20 Meeting ID: 832 4345 1066=20 Passcode: NYCCTS1=20 Seminar web page. =20 Videoed talks. =20 Previous semesters. researchseminars.org page. =20 Contact N. Yanofsky to schedule a speaker=20 or to add a name to the seminar mailing list.=20 _____ =20 _____ =20 Fall 2023=20 _____ =20 _____ =20 =20 =20 * Speaker: Tom=E1=B9 Gonda, University of Innsbruck.=20 * Date and Time: Wednesday September 27, 2023, 5:00 - 6:00 PM. ZOOM TALK. NOTE SPECIAL TIME!=20 * Title: A Framework for Universality in Physics, Computer Science, = and Beyond.=20 * Abstract: Turing machines and spin models share a notion of = universality according to which some simulate all others. We set up a categorical framework for universality which includes as instances universal Turing machines, universal spin models, NP completeness, top of a preorder, denseness of a subset, and others. By identifying necessary conditions = for universality, we show that universal spin models cannot be finite. We = also characterize when universality can be distinguished from a trivial one = and use it to show that universal Turing machines are non-trivial in this = sense. We leverage a Fixed Point Theorem inspired by a result of Lawvere to establish that universality and negation give rise to unreachability = (such as uncomputability). As such, this work sets the basis for a unified approach to universality and invites the study of further examples = within the framework.=20 _____ =20 =20 * Speaker: Thiago Alexandre, ???.=20 * Date and Time: Wednesday October 11, 2023, 7:00 - 8:30 PM.=20 * Title: ...derivator.... .=20 * Abstract:=20 _____ =20 =20 * Speaker: Michael Shulman, University of San Diego.=20 * Date and Time: Wednesday October 18, 2023, 7:00 - 8:30 PM.=20 * Title: The derivator of setoids.=20 * Abstract:=20 _____ =20 =20 * Speaker: Emilio Minichiello, CUNY Graduate Center.=20 * Date and Time: Wednesday October 25, 2023, 7:00 - 8:30 PM. IN = PERSON TALK.=20 * Title: A Mathematical Model of Package Management Systems.=20 * Abstract: In this talk, I will review some recent joint work with Gershom Bazerman and = Raymond Puzio. The motivation is simple: provide a mathematical model of package management systems, such as the Hackage package respository for Haskell, = or Homebrew for Mac users. We introduce Dependency Structures with Choice = (DSC) which are sets equipped with a collection of possible dependency sets = for every element and satisfying some simple conditions motivated from real = life use cases. We define a notion of morphism of DSCs, and prove that the resulting category of DSCs is equivalent to the category of = antimatroids, which are mathematical structures found in combinatorics and computer science. We analyze this category, proving that it is finitely complete, = has coproducts and an initial object, but does not have all coequalizers. Further, we construct a functor from a category of DSCs equipped with a certain subclass of morphisms to the opposite of the category of finite distributive lattices, making use of a simple finite characterization of = the Bruns-Lakser completion.=20 _____ =20 =20 * Speaker: Larry Moss, Indiana University, Bloomington .=20 * Date and Time: Wednesday November 8, 2023, 7:00 - 8:30 PM. ZOOM = TALK=20 * Title: On Kripke, Vietoris, and Hausdorff Polynomial Functors.=20 * Abstract: The Vietoris space of compact subsets of a given Hausdorff space yields an endofunctor V on the category of Hausdorff spaces. = Vietoris polynomial endofunctors on that category are built from V, the identity = and constant functors by forming products, coproducts and compositions. = These functors are known to have terminal coalgebras and we deduce that they = also have initial algebras. We present an analogous class of endofunctors on = the category of extended metric spaces, using in lieu of V the Hausdorff = functor H. We prove that the ensuing Hausdorff polynomial functors have terminal coalgebras and initial algebras. Whereas the canonical constructions of terminal coalgebras for Vietoris polynomial functors takes omega steps, = one needs \omega + \omega steps in general for Hausdorff ones. We also give = a new proof that the closed set functor on metric spaces has no fixed = points.=20 _____ =20 =20 * Speaker: Pedro Sota, TBA.=20 * Date and Time: Wednesday November 22, 2023, 7:00 - 8:30 PM.=20 * Title: TBA.=20 * Abstract:=20 [For admin and other information see: http://www.mta.ca/~cat-dist/ ]