Évènement

Naomi Andrew
institut de mathématiques, université d'Oxford (Royaume-Uni)
https://naomigandrew.wordpress.com/

Date(s) : 11/10/2024   iCal
11h00 - 12h00

Since their introduction by Bestvina and Handel, train tracks — particularly nice topological representatives — and their generalisations have provided an important way of understanding (irreducible) automorphisms of a free group. One of the invariants we can associate to (the conjugacy class of) an automorphism is its stretch factor: how fast elements grow under iteration of that automorphism, and this data is captured by its train track map, and by the dynamics associated to its action on Culler–Vogtmann outer space.

I will discuss recent work with Hillen, Lyman and Pfaff where we characterise the smallest stretch factor among expanding elements of Out(F_3), and show that the element realising it has among the simplest possible train track representatives. If time allows, I will also discuss an application to profinite rigidity of free-by-cyclic groups.

Emplacement
Saint-Charles - FRUMAM (2ème étage)

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