2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/32170How to extract negative information from programs is an important issue in logic programming. Here we address the problem for functional logic programs, from a proof-theoretic perspective. The starting point of our work is CRWL (Constructor based ReWriting Logic), a well established theoretical framework for functional logic programming, whose fundamental notion is that of non-strict non-deterministic function. We present a proof calculus, CRWLF, which is able to deduce negative information from CRWL-programs. In particular, CRWLF is able to prove finite failure of reduction within CRWL.Appeared in Theory and Practice of Logic Programming, vol. 4, no. 1&2, 2004Programming LanguagesD.1.6; D.3.2text