Monday November 20th at 4.30pm

solution, however, does not provide a "nice" certificate of optimality. We prove a min-max relation for FVS on series-parallel

graphs with no induced subdivision of K2,3 (a class of graphs containing the outerplanar graphs), thereby establishing the existence

of nice certificates for these graphs. Our proof relies on the description of a complete set of inequalities defining the feedback

vertex set polytope of a series-parallel graph with no induced subdivision of K2,3. We also prove that many of the inequalities

described are facets of this polytope.

This is joint work with Samuel Fiorini, from the Universite Libre de Bruxelles.