Conférencière : Kathryn Mann, Cornell

Résumé : A "bifoliation" of a two-dimensional space is a way of covering it with local charts to the Euclidean plane R^2 so that overlap maps in R^2 match up the vertical and horizontal coordinate directions.  Such objects arise naturally in many dynamical contexts such as Anosov diffeomorphisms on surfaces, or flows on 3-manifolds.A trick due to Mather lets one compactify a bifoliated plane with a "circle at infinity" using the data of the bifoliation.  In recent work with Barthelmé and Bonatti, we studied the inverse question: what is the minimum amount of data from infinity that allows one to reverse this procedure and uniquely reconstruct a bifoliation of the plane?   This talk will explain the answer!  While our motivation for this question was the problem of classifying pseudo-Anosov flows, the problem and solution are entirely in the realm of low-dimensional topology.