Adaptive CHR meets CHRv: An extended refined operational semantics for CHRv based on justifications

Adaptive constraint processing with Constraint Handling Rules (CHR) allows the application of intelligent search strategies to solve Constraint Satisfaction Problems (CSP), but these search algorithms have to be implemented in the host language of adaptive CHR which is currently Java. On the other hand, CHRv enables to explicitly formulate search in CHR, using disjunctive bodies to model choices. However, a naive implementation for handling disjunctions, in particular chronological backtracking (as implemented in Prolog), might cause "thrashing" due to an inappropriate order of decisions. In order to avoid this, a first combination of adaptive CHR and CHRv is presented to offer a more efficient embedded search mechanism to handle disjunctions. Therefore, the refined operational semantics of CHR is extended for disjunctions and adaptation.