NP-SPEC: an executable specification language for solving all problems in NP

In this paper a logic-based specification language, called NP-SPEC, is presented. The language is obtained by extending DATALOG through allowing a limited use of some second-order predicates of predefined form. NP-SPEC programs specify solutions to problems in a very abstract and concise way, and are executable. In the present prototype they are compiled to PROLOG code, which is run to construct outputs. Second-order predicates of suitable form allow to limit the size of search spaces in order to obtain reasonably efficient construction of problem solutions. NP-SPEC expressive power is precisely characterized as to express exactly the problems in the class NP. The specification of several combinatorial problems in NP-SPEC is shown, and the efficiency of the generated programs is evaluated.