BEGIN:VCALENDAR VERSION:2.0 PRODID:researchseminars.org CALSCALE:GREGORIAN X-WR-CALNAME:researchseminars.org BEGIN:VEVENT SUMMARY:Todd Trimble (Western Connecticut State University) DTSTART:20211021T133000Z DTEND:20211021T143000Z DTSTAMP:20260423T021224Z UID:itaca/9 DESCRIPTION:Title: Gr othendieck groups of 2-rigs as lambda rings\nby Todd Trimble (Western Connecticut State University) as part of ItaCa Fest 2021\n\n\nAbstract\nTh is talk will report on recent joint work with John Baez and Joe Moeller. W e introduce a notion of 2-rig as a way of categorifying the usual notion o f rig (ring without negatives)\; examples include categories of group repr esentations\, categories of vector bundles over spaces\, categories of coh erent sheaves over projective varieties\, and many others. We describe Sch ur functors on general 2-rigs\, and indicate how the free 2-rig on one gen erator encodes Schur functors on 2-rigs. Finally\, we indicate how the Gro thendieck group of a 2-rig yields a lambda ring\, where the theory of lamb da-rings is a “plethory” obtained by decategorifying a conceptually si mple 2-plethory that is associated with the free 2-rig.\n LOCATION:https://researchseminars.org/talk/itaca/9/ END:VEVENT END:VCALENDAR