Pruning External Minimality Checking for ASP Using Semantic Dependencies

HEX programs integrate external computations in ASP. For HEX-evaluation, an external (e)-minimality check is required to prevent cyclic justifications via external sources. As the check is a bottleneck in practice, syntactic information about atom dependencies has been used previously to detect when the check can be avoided. However, the approach largely overapproximates the real dependencies due to the blackbox nature of external sources. We show how the dependencies can be approximated more closely by exploiting semantic information, which significantly increases pruning of e-minimality checking. Moreover, we analyze checking and optimization of semantic dependency information. An empirical evaluation exhibits a clear benefit of this approach.