Conjunctive grammars with restricted disjunction



: Okhotin Alexander, Reitwiessner Christian

Publisher: ELSEVIER SCIENCE BV

: 2010

: Theoretical Computer Science

: THEORETICAL COMPUTER SCIENCE

: THEOR COMPUT SCI

: 26-28

: 411

: 26-28

: 2559

: 2571

: 13

: 0304-3975

DOI: https://doi.org/10.1016/j.tcs.2010.03.015


It is shown that every conjunctive language is generated by a conjunctive grammar from a special subclass, in which every nonterminal A has at most one rule of the general form A -> alpha(1)& ... &alpha(n), while the rest of the rules for A must be of the type A -> w, where w is a terminal string. For context-free grammars, a similar property does not hold (S.A. Greibach et al. (1992)[3]). If it is furthermore required that each rule A -> w has a nonempty w, then a substantial subfamily of conjunctive languages can be generated, yet it remains unknown whether such grammars are as powerful as conjunctive grammars of the general form. (C) 2010 Elsevier B.V. All rights reserved.



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