Dear colleagues, We would like to recall that the Days of the Federation de Recherche en Mathématiques de Paris Centre will take place on Monday 19, Tuesday 20 and Wednesday 21 May at the Institute Henri Poincare. This workshop is part of the thematic trimester « Semantics of Proofs and Certified Mathematics » currently held at Institut Henri Poincare, and will be devoted to the general theory of operads and to its applications. The workshop will offer us the occasion to listen the following speakers: Mathieu ANEL (ETH Zurich) John BAEZ (U.C. Riverside) Frédéric CHAPOTON (Institut Camille Jordan, Université Claude Bernard Lyon 1) Eric FINSTER (Université Paris Diderot) Benoit FRESSE (Laboratoire Painlevé, Université Lille 1) Nicola GAMBINO (University of Leeds) Ezra GETZLER (Northwestern University) Martin HYLAND (University of Cambridge) Joachim KOCK (Université Autonome de Barcelone) Muriel LIVERNET (Institut Galilée, Université Paris Nord) Philippe MALBOS (Institut Camille Jordan, Université Claude Bernard Lyon 1) Emily RIEHL (Harvard University) Gabriele VEZZOSI (Université Paris Diderot) You will find a detailed program of the workshop here: https://ihp2014.pps.univ-paris-diderot.fr/doku.php?id=federation The organizers, Pierre-Louis Curien Paul-André Melliès [For admin and other information see: http://www.mta.ca/~cat-dist/ ]