NVNF-sequentiality of Left-linear Term Rewriting Systems

This paper introduces NVNF-sequentiality which is an extension of NV-sequentiality defined by Oyamaguchi. It is shown that the class of NVNF-sequential systems properly includes the class of -sequential systems, and the indices with respect to NVNFsequentiality are computed for a given term when a term rewriting system is NVNFsequential. NVNF-sequentiality is decidable, and the index reduction is normalizing strategy for NVNF-sequential orthogonal term rewriting systems.