Abstract. We describe DysToPic, a theorem prover for the preferential Description Logic ALC + Tmin.This is a nonmonotonic extension of standard ALC based on a typicality operator T, which enjoys a preferential semantics. DysToPic is a multi-engine Prolog implementation of a labelled, two-phase tableaux calculus for ALC + Tmin whose basic idea is that of performing these two phases by different machines. The performances of DysToPic are promising, and significantly better than the