On representing RE languages by one-sided internal contextual languages
In this paper we prove that each recursively enumerable language can be written in the form , where is a language generated by a one-sided internal contextual grammar with context-free choice, is a regular language, and is the operation which removes the prefix bounded by the special symbol , which appears exactly once in the strings for which is defined.
However, the context-free choice sets are always deterministic linear languages of a very simple form. Similar representations can be obtained using one-sided contextual grammars with finite choice and with erased or with erasing contexts.
Keywords. Formal languages, contextual grammars, recursively enumerable languages.
Gyenizse Pal 1997. Február 4. Kedd 15:09:10 MET