Veech surface

In mathematics, a Veech surface is a translation surface (X,ω) (a Riemann surface X with a holomorphic 1-form ω) whose group SL(X,ω) of affine diffeomorphisms is a lattice in SL₂(R) (a discrete subgroup of cofinite volume). The image of SL(X,ω) in PSL₂(R) is called the Veech group.