Analogical Conception of Chomsky Normal Form and Greibach Normal Form for Linear, Monadic Context-Free Tree Grammars


IEICE TRANSACTIONS on Information and Systems   Vol.E89-D   No.12   pp.2933-2938
Publication Date: 2006/12/01
Online ISSN: 1745-1361
DOI: 10.1093/ietisy/e89-d.12.2933
Print ISSN: 0916-8532
Type of Manuscript: PAPER
Category: Automata and Formal Language Theory
formal languages,  tree adjoining grammar,  mildly context-sensitive grammar,  context-free tree grammar,  

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This paper presents the analogical conception of Chomsky normal form and Greibach normal form for linear, monadic context-free tree grammars (LM-CFTGs). LM-CFTGs generate the same class of languages as four well-known mildly context-sensitive grammars. It will be shown that any LM-CFTG can be transformed into equivalent ones in both normal forms. As Chomsky normal form and Greibach normal form for context-free grammars (CFGs) play a very important role in the study of formal properties of CFGs, it is expected that the Chomsky-like normal form and the Greibach-like normal form for LM-CFTGs will provide deeper analyses of the class of languages generated by mildly context-sensitive grammars.