This chapter gives an extensive and thorough coverage of grammars that generate languages under various context -related restrictions. First, it covers classical grammars based upon tight context restrictions. Then, it studies context conditional grammars and their variants, including random context grammars, generalized forbidding grammars, semi-conditional grammars, and simple semi-conditional grammars. They all are based upon loose context restrictions. More precisely, they have their rules enriched by permitting and forbidding strings, referred to as permitting and forbidding conditions, respectively. These grammars perform their language-generation process in such a way that they require the presence of permitting conditions and, simultaneously, the absence of forbidding conditions in the rewritten sentential forms.

Chapter Contents:

• 11.1 Tightly context-dependent grammars
• 11.2 Loosely context-dependent grammars

Inspec keywords: rewriting systems; context-free grammars

Other keywords: random context grammars; language-generation process; semiconditional grammars; tight context restrictions; rewritten sentential forms; context-related restrictions; context-dependent grammars

Subjects: Formal languages and computational linguistics