On the Expressive Power of Dynamic Logic

Abstract

We show that "looping" of while-programs can be expressed in Regular First Order Dynamic Logic, disproving a conjecture made by Harel and Pratt. In addition we show that the expressive power of quantifier-free Dynamic Logic increases when nondeterminism is introduced in the programs that are part of formulae of Dynamic Logic. Allowing Assignments of random values to variables also increases expressive power.