Efficient algorithms for automatic construction and compactification of parsing

Abstract

Several computational problems about grammars are studied. Efficient algorithms are presented for the problems of (1) determining, for a given semantic grammar, if there exists a related parsing grammar in some specified grammar class, and (2) finding such a related parsing grammar when one exists. The two grammars are to be related by mergers of nonterminals and/or terminals. Efficient algorithms are presented for most of the grammar classes used in compilers. We also study the problem of (3) determining which terminals of a grammar are good candidates for merger into common lexical tokens of the corresponding parsing grammar.