Algebra seminar  January 9, 1pm, lecture room M5 


We will continue on Thursday, January 9, in M5 at 1pm by the talk
S. Henry
Polygraphs and homotopy polygraphs
Abstract: Polygraphs (or computades) are the most general notion of diagram generating strict infinity categories. Some people have believed in the past that they were a presheaves category, but this was proved to be false by Makkai and Zawadowski. After a quick introduction to polygraphs and why they are not a presheaves category, I'll show that if one defines a homotopy theoretic (or infinity categorical) version of polygraphs then they form an infinity presheaves category. More generally I'll associate to any strongly cartesian monad acting on an infinity topos an infinity category of polygraphs which is itself an infinity topos. 
Last Updated on Tuesday, 07 January 2020 16:37 

MUNI Seminar series  Noga Alon  List Coloring 


December 18, 2019 from 4:30 PM at Refectory of Augustinian Abbey at Mendel Square  Mendel Museum
List Coloring
Abstract:
The list chromatic number of a graph G is the minimum k so that for every assignment of a list of k colors to any vertex of G there is a vertex coloring assigning to each vertex a color from its list so that adjacent vertices get distinct colors. This notion was introduced by Vizing and by Erdős, Rubin and Taylor in the late 70s and its study combines combinatorial, probabilistic and algebraic techniques.
Its natural extension to hypergraphs is closely related to questions in Euclidean Ramsey Theory. I will discuss several old and new problems and results in the area focusing on a recent work with Briceno, Chandgotia, Magazinov and Spinka motivated by questions in statistical physics regarding vertex colorings of the ddimensional lattice. 
Last Updated on Wednesday, 18 December 2019 12:01 
27th mathematical hike  December 14th 2019 


Dear Friends of Hikes and Mathematics,
you are invited to our 27th mathematical hike planned on December 14th. Meet at 09:36 at the bus stop "Rozcestí" (bus 57) in Útěchov. We have planned a short hike (not even 10 km) not following any tourist path towards the ruins of Ronov castle. The end of the hike is in Útěchov. Snow or mud, doesn't matter, look forward to a Christmas hike. All information and photos can be found at http://conference.math.muni.cz/vylety/. (in CZ) Have a nice December, Jonatan Kolegar and Jana Bartoňová, organizers, Jan Slovák, Director of the Department of Mathematics and Statistics 
Last Updated on Thursday, 12 December 2019 11:24 
Differential geometry seminar  December 2, 10am, lecture room M5 


The seminar on differential geometry will continue with this lecture:
December 2, 10am, lecture room M5.
Vincent Pecastaing (University of Luxembourg):
Actions of higherrank lattices on conformal and projective structures
Abstract:
The main idea of Zimmer's program is that in realrank at least 2, the rigidity of lattices of semisimple Lie groups makes that their actions on closed manifolds are understandable. After a short survey giving a more precise idea of Zimmer's conjectures and their context, I will give recent results about conformal and projective actions of cocompact lattices. The fact that these geometric structures do not carry a natural invariant volume is one of the main motivations. We will see that the realrank is bounded above like when the ambient Lie group is acting, and that at the critical value, the manifold is globally isomorphic to a model homogeneous space. The proofs rely in part on an "invariance principle" recently introduced by Brown, RodriguezHertz and Wang, which guarantees the existence of finite invariant measures in some dynamical context. 
Last Updated on Friday, 29 November 2019 14:38 
Differential equations seminar  December 2, 12pm, lecture room M5 


Seminar of differential equations will continue on December 2, 2019 at 12pm in lecture room M5.
Dr. Rotchana Chieochan (Khon Kaen University, Thajsko)
Floquet theory for qdifference equations
Abstract:
In this talk, we introduce qperiodic functions in quantum calculus and study the firstorder linear qdifference vector equation for which its coefficient matrix function is qperiodic and regressive. Based on the new definition of periodic functions, we establish Floquet theory in quantum calculus. 
Last Updated on Tuesday, 26 November 2019 12:03 

