QCSP made Practical by virtue of Restricted Quantification
Marco Benedetti, Arnaud Lallouet, Jérémie Vautard
The QCSP+ language we introduce extends the framework of Quantified Constraint Satisfaction Problems (QCSPs) by enabling us to neatly express restricted quantifications via a chain of nested CSPs to be interpreted as alternately conjuncted and disjuncted. Restricted quantifiers turn out to be a convenient solution to the crippling modeling issues we encounter in QCSP and — surprisingly — they help to reuse propagation technology and to prune the search space. Our QCSP+ solver — which also handles arithmetic and global constraints — exhibits state-of-the-art performances.