Generating diagnostic information for behavioral preorders

Summary.  This paper describes a method for generating diagnostic information that explains why a given finite-state system fails to be greater than its specification with respect to the prebisimulation preorder. The information takes the form of a logical formula satisfied by the specification but not by the system and thus may be used by system designers for debugging purposes. Our technique relies on modifying an algorithm for computing the prebisimulation preorder so that information needed for generating these distinguishing formulas is saved appropriately. As a number of other behavioral preorders may be characterized in terms of prebisimulation preorder, our approach may be used as a basis for computing diagnostic information for these relations as well. Received: August 1992/Accepted: May 1995