01097815

j

01097815 Latteux, M. Simplot, D. Context-sensitive string languages and recognizable picture languages. Inf. Comput. 138, No.2, 160-169 (1997). 1997 Elsevier Science (Academic Press), San Diego, CA EN recognizable tree languages context-free languages Zbl 0155.34301

doi:10.1006/inco.1997.2659

Summary: The theorem stating that the family of frontiers of recognizable tree languages is exactly the family of context-free languages [see {\it J. Mezei} and {\it J. B. Wright}, Inf. Control 11, 3-29 (1967; Zbl 0155.34301)], is a basic result in the theory of formal languages. In this article, we prove a similar result: the family of frontiers of recognizable picture languages is exactly the family of context-sensitive languages.