Online algebra seminar  May 6th, 2pm 


We will continue online on Thursday, May 6th, the special time of 14.00 CEST on ZOOM platform (for information how to acces seminar and next programme visit this page) by the talk:
Walter Tholen
Spaces vs Categories, Perfect Maps vs Discrete Cofibrations
Abstract: We consider perfect maps of topological spaces and discrete cofibrations of categories to guide us into Burroni's notions of Tcategory and Tfunctor. In that environment we establish a socalled comprehensive factorization system that entails the classical StreetWalters system, as well as the (antiperfect, perfect)system for continuous maps of Tychonoff spaces known since the 1960s. (Based on joint work with Leila Yeganeh) 
Last Updated on Tuesday, 04 May 2021 10:09 

Online algebra seminar  April 29th, 1pm 


We will continue online on Thursday, April 29th, at 1pm on ZOOM platform (for information how to acces seminar and next programme visit this page) by the talk:
Hoang Kim Nguyen
Contravariant Homotopy Theories and Quillen’s Theorem A
Abstract: In this talk I will show how to construct a model structure on a locally presentable category with a suitable cylinder object such that the model structure behaves in a ”covariant” or ”contravariant” way with respect to the cylinder. Examples of such model structures include the covariant and contravariant model structures on simplicial sets and the cocartesian and cartesian model structures on marked simplicial sets modelling presheaves with values in ∞groupoids and ∞categories respectively. The model structures come with an abstract notion of cofinal functor which recovers the usual definition of cofinal functor for ∞categories when applied to the covariant and contravariant model structures on simplicial sets. When applied to presheaves valued in ntypes, one obtains a version of Quillen’s Theorem A for ncategories. 
Last Updated on Friday, 23 April 2021 08:24 
Habilitation lecture on April 27, 2021: John Bourke, PhD. 


Dear colleagues, let me invite you to the habilitation lecture of John Bourke, PhD., which will be held on Tuesday, April 27, 2021, at 16 via Zoom https://cesnet.zoom.us/j/92131900502?pwd=blduc1JWRGhobU5DSHJXVkNDWmxIdz09 Meeting ID: 921 3190 0502 Passcode: 510616 TITLE: Factorisation systems in algebra and homotopy theory. Jiří Rosický Chairman of the Habilitation Board 
Last Updated on Tuesday, 20 April 2021 08:09 
Online algebra seminar  April 15th, 1pm 


We will continue online on Thursday, April 15th, at 1pm on ZOOM platform (for information how to acces seminar and next programme visit this page) by the talk:
Mark Kamsma
Independence Relations in Abstract Elementary Categories
Abstract: In Shelah's classification of firstorder theories we classify theories using combinatorial properties. The most wellknown class is that of stable theories, which are very wellbehaved. Simple theories are more general, and then even more general are the NSOP_1 theories. We can characterise those classes by the existence of a certain independence relation. For example, in vector spaces such an independence relation comes from linear independence. Part of this characterisation is canonicity of the independence relation: there can be at most one nice enough independence relation in a theory. Lieberman, Rosický and Vasey proved canonicity of stablelike independence relations in accessible categories. Inspired by this we introduce the framework of AECats (abstract elementary categories) and prove canonicity for simplelike and NSOP_1like independence relations. This way we reconstruct part of the hierarchy that we have for firstorder theories, but now in the very general categorytheoretic setting. 
Last Updated on Tuesday, 13 April 2021 08:34 
Habilitation lecture: Dr. András Rontó, Ph.D. (Brno University of Technology) 


We invite you to the habilitation lecture of Dr. András Rontó, Ph.D. (Brno University of Technology), which will be held in the seminar on differential equations on Monday, April 19, 2021, at 12 via Zoom.
Link here: https://cesnet.zoom.us/j/91705657887
TITLE: CONSTRUCTIVE ANALYSIS OF BOUNDARY VALUE PROBLEMS FOR ORDINARY DIFFERENTIAL EQUATIONS 
Last Updated on Monday, 12 April 2021 11:14 

