The Independence of Inherent Ambiguity From Complementedness Among Context-Free Languages
- 1 October 1966
- journal article
- Published by Association for Computing Machinery (ACM) in Journal of the ACM
- Vol. 13 (4) , 588-593
- https://doi.org/10.1145/321356.321366
Abstract
Call a (context-free) language unambiguous if it is not inherently ambiguous. In the absence of evidence to the contrary, the suspicion has arisen that the unambiguous languages might be precisely those languages with context-free complements. The two theorems presented in this paper lay the suspicion to rest by providing (1) an inherently ambiguous language with context-free complement and (2) an unambiguous language without context-free complement. This establishes the independence of inherent ambiguity from complementedness among the context-free languages.Keywords
This publication has 2 references indexed in Scilit:
- Semigroups, Presburger formulas, and languagesPacific Journal of Mathematics, 1966
- Ambiguity in context free languagesJournal of the ACM, 1966