Periodically time-variant context-free grammars

Modularized Context-Free Grammars

Given two context-free grammars (CFGs), G 1 and G 2 , the language generated by the union of the grammars is not the union of the languages generated by each grammar: L(G 1 G 2) 6 = L(G 1) L(G 2). In order to account for mod-ularity of grammars, another way of deening the meaning of grammars is needed. This paper adapts results from the semantics of logic programming languages to CFGs. We discu...

Multiple Context-Free Grammars

Multiple context-free grammar (MCFG) is a weakly contextsensitive grammar formalism that deals with tuples of strings. An MCFG is called m-MCFG if all tuples have at most m components. In this summary I will outline that the expressivity of m-MCFG’s increases with the parameter m and that the class of tree-adjoining languages is properly included in the class of 2-multiple context-free language...

Context-Free Graph Grammars

Graph grammars have been studied by several authors. The motivations of these works have arisen from completely different areas of computer science, such as picture processing (Pfaltz and Rosenfeld, 1969; Montanari, 1970; Rosenfeld and Milgram, 1972; Pavlidis, 1972; Abe et al., 1973; Furtado and Mylopoulos, 1975; Fu and Brayer, 1975) or formal semantics of programming languages (Pratt, 1971). I...

Modular Context-Free Grammars

Multiple Context Free Grammars

Multiple context-free grammars (MCFGs) are a generalization of context-free grammars that deals with tuples of strings. This is a brief survey of MCFGs, their properties, and their relations to other formalisms. We outline simple constructions to convert MCFGs to Hyperedge Replacement Grammars (HRGs) and to Deterministic Tree Walking Transducers (DTWTs), and also to simulate DTWTs by MCFGs. We ...