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:20240310T070000 END:DAYLIGHT BEGIN:STANDARD TZNAME:EST TZOFFSETFROM:-0400 TZOFFSETTO:-0500 DTSTART:20231105T060000 END:STANDARD END:VTIMEZONE BEGIN:VEVENT UID:69f44f17d6437 DTSTART;TZID=America/Toronto:20240403T143000 SEQUENCE:0 TRANSP:TRANSPARENT DTEND;TZID=America/Toronto:20240403T153000 URL:https://uwaterloo.ca/pure-mathematics-logic/events/undecidable-extensio n-morleys-theorem-number-countable SUMMARY:An undecidable extension of Morley’s theorem on the number of\nco untable models CLASS:PUBLIC DESCRIPTION:FRANKLIN TALL\, UNIVERSITY OF TORONTO\n\nWe show that Morley’ s theorem on the number of countable models of a\ncountable first-order th eory becomes an undecidable statement when\nextended to second-order logic . More generally\, we calculate the\nnumber of equivalence classes of equi valence relations obtained by\ncountable intersections of projective sets in several models of set\ntheory. Our methods include random and Cohen for cing\, large cardinals\,\nand Inner Model Theory.\n\nMC 5479 DTSTAMP:20260501T065831Z END:VEVENT BEGIN:VEVENT UID:69f44f17d8686 DTSTART;TZID=America/Toronto:20240327T143000 SEQUENCE:0 TRANSP:TRANSPARENT DTEND;TZID=America/Toronto:20240327T153000 URL:https://uwaterloo.ca/pure-mathematics-logic/events/binding-groups-ratio nal-dynamics SUMMARY:Binding groups for rational dynamics CLASS:PUBLIC DESCRIPTION:RAHIM MOOSA\, DEPARTMENT OF PURE MATHEMATICS\, UNIVERSITY OF WA TERLOO\n\nI will report on ongoing work with Moshe Kamensky toward develop ing a\ntheory of binding groups for quantifier-free types in ACFA\,\nwell- suited for applications to rational algebraic dynamics.\n\nMC 5479 DTSTAMP:20260501T065831Z END:VEVENT BEGIN:VEVENT UID:69f44f17d8f4e DTSTART;TZID=America/Toronto:20240320T143000 SEQUENCE:0 TRANSP:TRANSPARENT DTEND;TZID=America/Toronto:20240320T153000 URL:https://uwaterloo.ca/pure-mathematics-logic/events/klein-j-function-not -pfaffian-over-real-exponential-field SUMMARY:The Klein j-Function is not Pfaffian over the Real Exponential Fiel d CLASS:PUBLIC DESCRIPTION:CHRISTOPH KESTING\, MCMASTER UNIVERSITY\n\nJames Freitag showed that the Klein j-function is not pfaffian over\nthe complex numbers. In t his talk\, I will give a brief introduction to\npfaffian functions\, their current place in model theory and Freitag's\nresult. Then I will discuss recent work expanding Freitag's result to\na restriction of the j-function to the imaginary interval (0\, i) not\nbeing pfaffian over the real expo nential field.\n\nMC 5479 DTSTAMP:20260501T065831Z END:VEVENT BEGIN:VEVENT UID:69f44f17d980d DTSTART;TZID=America/Toronto:20240313T143000 SEQUENCE:0 TRANSP:TRANSPARENT DTEND;TZID=America/Toronto:20240313T153000 URL:https://uwaterloo.ca/pure-mathematics-logic/events/isomorphism-spectra- and-computably-composite-structures SUMMARY:Isomorphism Spectra and Computably Composite Structures CLASS:PUBLIC DESCRIPTION:JOEY LAKERDAS-GAYLE\, DEPARTMENT OF PURE MATHEMATICS\, UNIVERSI TY OF\nWATERLOO\n\nIf $\\mathcal{A}$ and $\\mathcal{B}$ are two computable copies of a\nstructure\, their isomorphism spectrum is the set of Turing degrees\nthat compute an isomorphism from $\\mathcal{A}$ to $\\mathcal{B}$ . We\nintroduce a framework for constructing computable structures with th e\nproperty that the isomorphisms between arbitrary computable copies of\n these structures are constructed from isomorphisms between computable\ncop ies of their component structures. We call these \\emph{computably\ncompos ite structures}. We show that given any uniformly computable\ncollection o f isomorphism spectra\, there exists a pair of computably\ncomposite struc tures whose isomorphism spectrum is the union of the\noriginal isomorphism spectra. We use this to construct examples of\nisomorphism spectra that a re not equal to the upward closure of any\nfinite set of Turing degrees.\n \nMC 5479 DTSTAMP:20260501T065831Z END:VEVENT BEGIN:VEVENT UID:69f44f17d9ff7 DTSTART;TZID=America/Toronto:20240306T143000 SEQUENCE:0 TRANSP:TRANSPARENT DTEND;TZID=America/Toronto:20240306T153000 URL:https://uwaterloo.ca/pure-mathematics-logic/events/splitting-differenti al-logarithm-map-using-galois-theory SUMMARY:Splitting the differential logarithm map using Galois theory CLASS:PUBLIC DESCRIPTION:CHRISTINE EAGLES\, DEPARTMENT OF PURE MATHEMATICS\, UNIVERSITY OF\nWATERLOO\n\nAn ordinary algebraic differential equation is said to be internal to\nthe constants if its general solution is obtained as a ration al\nfunction of finitely many of its solutions and finitely many constant\ nterms. Such equations give rise to algebraic groups behaving as Galois\ng roups. In this talk I give a characterisation of when the pullback of\nthe differential logarithm of an equation is internal to the constants\nwhen the Galois group is unipotent or a torus. This is joint work in\nprogress with Leo Jimenez.\n\nMC 5479 DTSTAMP:20260501T065831Z END:VEVENT BEGIN:VEVENT UID:69f44f17da766 DTSTART;TZID=America/Toronto:20240228T143000 SEQUENCE:0 TRANSP:TRANSPARENT DTEND;TZID=America/Toronto:20240228T153000 URL:https://uwaterloo.ca/pure-mathematics-logic/events/computable-continuou s-logic-qwep-and-type-iii-factors SUMMARY:Computable Continuous Logic\, QWEP\, and Type III Factors CLASS:PUBLIC DESCRIPTION:JANANAN ARULSEELAN\, MCMASTER UNIVERSITY\n\nBy the recent MIP*= RE result\, the QWEP conjecture is known to be\nfalse. Consequently\, the universal theory of the hyperfinite II_1\nfactor is not computable. We wil l explain these results and their\ncontext and then discuss the uncomputab ility of the universal theories\nof other Powers factors and the lack of a n effective axiomatization of\nQWEP C^∗ algebras. As an application we s how that there is a\nultraproduct of non-QWEP algebras with QWEP. This is joint work with\nIsaac Goldbring and Bradd Hart. \n\nMC 5479 DTSTAMP:20260501T065831Z END:VEVENT BEGIN:VEVENT UID:69f44f17daf1e DTSTART;TZID=America/Toronto:20240214T143000 SEQUENCE:0 TRANSP:TRANSPARENT DTEND;TZID=America/Toronto:20240214T153000 URL:https://uwaterloo.ca/pure-mathematics-logic/events/continuous-stable-re gularity SUMMARY:Continuous Stable Regularity CLASS:PUBLIC DESCRIPTION:NICOLAS CHAVARRIA\, DEPARTMENT OF PURE MATHEMATICS\, UNIVERSITY OF\nWATERLOO\n\nWe discuss joint work with G. Conant and A. Pillay regard ing a version\nof the Malliaris-Shelah stable regularity lemma realized in the\ncontext of continuous logic\, which allows us to speak about the\nst ructure of stable functions of the form $f:V\\times W\\to [0\,1]$\,\nwhere we think of $V$ and $W$ as the parts of a \"weighted'' bipartite\ngraph. In the process\, we will also mention some results about the\nstructure of local Keisler measures in this setting.\n\nMC 5479 DTSTAMP:20260501T065831Z END:VEVENT BEGIN:VEVENT UID:69f44f17db6b8 DTSTART;TZID=America/Toronto:20240131T143000 SEQUENCE:0 TRANSP:TRANSPARENT DTEND;TZID=America/Toronto:20240131T153000 URL:https://uwaterloo.ca/pure-mathematics-logic/events/residually-finite-eq uational-theories SUMMARY:Residually finite equational theories CLASS:PUBLIC DESCRIPTION:ROSS WILLARD\, UNIVERSITY OF WATERLOO\n\nAn equational theory T is said to be residually finite if every model\nof the theory can be embe dded in a product of finite models of the\ntheory.  Equivalently\, T is r esidually finite if and only if its\nirreducible models (those that cannot be embedded in products of\n“simpler” models) are all finite.  In pr actice\, it seems that\nwhenever a theory is both “interesting” and re sidually finite\,\nthen there is a finite upper bound to the sizes of its irreducible\nmodels.  In other words\, we see a sort of compactness princ iple for\n“interesting” equational theories: if such a theory has\narb itrarily large finite irreducible models\, then it must have an\ninfinite irreducible model.  Whether or not this observation holds\ngenerally has been open for almost 50 years.  In this talk I will\ndiscuss some recent progress with collaborators Keith Kearnes and\nAgnes Szendrei.\n\nMC 5479 DTSTAMP:20260501T065831Z END:VEVENT BEGIN:VEVENT UID:69f44f17dbedb DTSTART;TZID=America/Toronto:20240124T143000 SEQUENCE:0 TRANSP:TRANSPARENT DTEND;TZID=America/Toronto:20240124T153000 URL:https://uwaterloo.ca/pure-mathematics-logic/events/generic-derivations- o-minimal-structures SUMMARY:Generic derivations on o-minimal structures CLASS:PUBLIC DESCRIPTION:ELLIOT KAPLAN\, MCMASTER UNIVERSITY\n\nLet T be a model complet e o-minimal theory that extends the theory of\nreal closed ordered fields (RCF). We introduce T-derivations:\nderivations on models of T which coope rate with T-definable functions.\nThe theory of models of T expanded by a T-derivation has a model\ncompletion\, in which the derivation acts \"gene rically.\" If T = RCF\,\nthen this model completion is the theory of close d ordered\ndifferential fields (CODF) as introduced by Singer. We can reco ver\nmany of the known facts about CODF (open core\, distality) in our\nse tting. We can also describe thorn-rank for models of T with a\ngeneric T-d erivation. This is joint work with Antongiulio Fornasiero.\n\nMC 5479 DTSTAMP:20260501T065831Z END:VEVENT BEGIN:VEVENT UID:69f44f17dc698 DTSTART;TZID=America/Toronto:20240117T143000 SEQUENCE:0 TRANSP:TRANSPARENT DTEND;TZID=America/Toronto:20240117T153000 URL:https://uwaterloo.ca/pure-mathematics-logic/events/sparse-subsets-reals SUMMARY:Sparse subsets of the reals CLASS:PUBLIC DESCRIPTION:JASON BELL\, DEPARTMENT OF PURE MATHEMATICS\, UNIVERSITY OF WAT ERLOO\n\nWe look at the first-order theory of the real numbers augmented b y a\npredicate X that is in some natural sense self-similar with respect t o\na positive integer base. We show that there is a dichotomy: either we\n can define a Cantor set in our structure or our expansion of the reals\nis interdefinable with the real numbers augmented by a set of the form\n{1/r \, 1/r^2\, 1/r^3\, …} for some integer r>=2.  In the latter case\,\nthi s is equivalent to the structure having NIP and NTP_2.  This is\njoint wo rk with Alexi Block Gorman.\n\nMC 5479 DTSTAMP:20260501T065831Z END:VEVENT END:VCALENDAR