A necessary condition for Constructive Negation in Constraint Logic Programming

Stuckey (1995) has presented a sound and complete procedure for Constructiv e Negation in Constraint Logic Programming, together with a sufficient cond ition, called admissible closure, which guarantees an effective implementat ion. In this paper we analyze this condition and relate it to the decidabil ity of the underlying constraint structure. We prove that the admissible cl osure condition is also necessary to guarantee the existence of an effectiv e implementation of Constructive Negation. (C) 2000 Elsevier Science B.V. A ll rights reserved.