A Variant of Pure Two-Dimensional Context-Free Grammars Generating Picture Languages

摘要

Considering a large variety of approaches in generating picture languages, the notion of pure two-dimensional context-free grammar (P2DCFG) represents a simple yet expressive non-isometric language generator of picture arrays. In the present paper, we introduce a new variant of P2DCFGs that generates picture arrays in a leftmost way. We concentrate our attention on determining their generative power by comparing it with the power of other picture generators. We also examine the power of these generators that regulate rewriting by control languages.