Discrete-Time Quantum Field Theory and the Deformed Super Virasoro   Algebra
  We show that the deformations of Virasoro and super Virasoro algebra, constructed earlier on an abstract mathematical background, emerge after Wick rotation, within an exact treatment of discrete-time free field models on a circle. The deformation parameter is $e^\lambda$, where $\lambda=\tau/\rho$ is the ratio of the discrete-time scale $\tau$ and the radius $\rho$ of the compact space. 
Masud Chaichian and Peter Presnajder