Synchronous Versions of Regulated Grammars: Generative Power and Linguistic Applications

This paper introduces the notion of new synchronous grammars as systems consisting of two context-free grammars with linked rules instead of linked nonterminals. Further, synchronous versions of regulated grammars, specifically, matrix grammars and scattered context grammars, are discussed. From a theoretical point of view, this paper discusses the power of these synchronous grammars. It demonstrates the following main results. First, if we synchronize context-free grammars by linking rules, the grammar generates the languages defined by matrix grammars. Second, if we synchronize matrix grammars by linking matrices, the generative power remains unchanged. Third, synchronous scattered context grammars generate the class of recursively enumerable languages. From a more practical viewpoint, this paper presents linguistic application prospects. The focus is on natural language translation between Japanese and English.