The goal of this workgroup i to read the papers Arboreal singularities by David Nadler, Arboreal singularities in Weinstein skeleta by Laura Starkston and Weinstein manifolds revisited, de Yakov Eliashberg, explaining a program aiming to reduce symplectic topology of Weinstein manifolds to algebra and combinatorics of especially simple skeleta. Talks will be in the new mathematics building in Orsay, building 307, in room 3L8 except for Thursday afternoon when we'll be in room 1A14.