Buongiorno,

segnalo a tutti gli interessati che il seminario di Yan Mary He si terrà Giovedì 10 Ottobre alle ore 11:00 presso l'Aula Riunioni del Dipartimento di Matematica. Allego titolo e abstract:

Titolo: Relative train tracks and endperiodic graph maps

Abstact: If G is a connected finite graph (i.e., G has finitely many vertices and edges), a graph map (i.e., a homotopy equivalence) f: G \to G can be viewed as a topological representative of an outer automorphism of the finitely generated free group \pi_1G. The outer automorphism group Out(F_n) of a free group F_n on n generators has been proven to share many similar properties of the mapping class group of a compact surface.

If G is an infinite graph (i.e.,G has infinitely many vertices and edges), the structure of a (proper) graph map f: G \to G is more complicated and less understood. Inspired by the recent work of Cantwell-Conlon-Fenley on homeomorphisms of infinite type surfaces, we introduce and study endperiodic graph maps f: G \to G where G has finitely many ends. We prove that any such a map is homotopic to an endperiodic relative train track map, which is a normal form for an endperiodic graph map. Moreover, we show that the Perron-Frobenius eigenvalue of the transition matrix is a canonical quantity associated to the map. This is joint work with Chenxi Wu.

link: https://www.dm.unipi.it/en/seminar/?id=66fbeae742845121abe42be8

A presto,

Carlo