User-Defined On-Demand Matching

Masaki NAKAMURA  Kazuhiro OGATA  Kokichi FUTATSUGI  

IEICE TRANSACTIONS on Information and Systems   Vol.E92-D   No.7   pp.1401-1411
Publication Date: 2009/07/01
Online ISSN: 1745-1361
DOI: 10.1587/transinf.E92.D.1401
Print ISSN: 0916-8532
Type of Manuscript: PAPER
Category: Computation and Computational Models
the evaluation strategy,  lazy evaluation,  on-demand matching,  term rewriting,  

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We propose a user-defined on-demand matching strategy, called O-matching, in which users can control the order of matching arguments of each operation symbol. In ordinary matching schemes it is not important to set the order of matching, however, in on-demand matching schemes, it is very important since an input term may be changed while doing the on-demand matching process. O-matching is suitable to combine with the E-strategy, which is a user-defined reduction strategy in which users can control the order of reducing arguments. We show a sufficient condition under which the E-strategy with O-matching is correct for head normal forms, that is, any reduced term is a head normal form.