From my notes:
In 1960, Queneau founded the Ouvroir de littérature potentielle, or Oulipo, with François le Lionnais. Other famous Oulipians include Georges Perec and Italo Calvino.
The society's guiding principles involved placing apparently arbitrary and frequently mathematical, lexical or logical constraints on a piece of work. These constraints might paradoxically "free" the creative spirit behind the work, leading to avant-garde inventiveness in its production. Indeed, unlike many other schools, Oulipo considered creativity to be very much an exercise in planned production.