Structured Counterexamples for the Temporal Description Logic ALCCTL

A new algorithm for generating counterexamples for the temporal description logic ALCCTL is presented. ALCCTL is a decidable combination of the description logic ALC and computation tree logic CTL. It extends CTL by first order quantified expressions over unary and binary predicates. Predicates and quantified expressions are required for representing properties in application domains such as structured web documents and they are frequently used in software and hardware specifications which are verified by model checking. In the case of a specification violation, existing algorithms generate counterexamples that tend to be complex yet imprecise if specifications range over sets of objects. The presented algorithm is the first algorithm for generating counterexamples for a temporal description logic that considers first order predicates and quantification. The algorithm is sound and semi-complete for ALCCTL. The generated counterexamples are both more precise and comprehensible than counterexamples generated by the previous algorithms.