Specifying and Exploiting Non-Monotonic Domain-Specific Declarative Heuristics in Answer Set Programming
This work addresses a bottleneck in combinatorial problem-solving for ASP users by enabling declarative heuristic specifications that depend on partial assignments, though it is incremental in extending existing ASP systems.
The authors tackled the problem of integrating non-monotonic domain-specific heuristics into Answer Set Programming (ASP), which was previously unsupported, and demonstrated that their approach enables solving industrial-size problems efficiently, as confirmed by experiments.
Domain-specific heuristics are an essential technique for solving combinatorial problems efficiently. Current approaches to integrate domain-specific heuristics with Answer Set Programming (ASP) are unsatisfactory when dealing with heuristics that are specified non-monotonically on the basis of partial assignments. Such heuristics frequently occur in practice, for example, when picking an item that has not yet been placed in bin packing. Therefore, we present novel syntax and semantics for declarative specifications of domain-specific heuristics in ASP. Our approach supports heuristic statements that depend on the partial assignment maintained during solving, which has not been possible before. We provide an implementation in ALPHA that makes ALPHA the first lazy-grounding ASP system to support declaratively specified domain-specific heuristics. Two practical example domains are used to demonstrate the benefits of our proposal. Additionally, we use our approach to implement informed} search with A*, which is tackled within ASP for the first time. A* is applied to two further search problems. The experiments confirm that combining lazy-grounding ASP solving and our novel heuristics can be vital for solving industrial-size problems.