Quantified Constraint Handling Rules

In this article, the QCSP (Quantified Constraint Satisfaction Problems) framework is shifted to the QCHR (Quantified Constraint Handling Rules) framework by enabling dynamic generation of quantifiers and access to user-defined constraints. QCSP offers a natural framework to express PSPACE problems as finite two-players games. But to define a QCSP model, the alternation of quantifiers must be formerly known and cannot be built dynamically even if the worst case will not occur. To overcome this issue, the new QCHR formalism, that allows to generate quantifiers dynamically during the solving, is defined. QCHR models exhibit state-of-the-art performances on a priori fixed alternation of quantifiers and outperforms previous QCSP approaches when the generation of quantifiers is dynamic.