Classes of picture languages that cannot be distinguished in the chain code concept and deletion of redundant retreats
- Cite this paper as:
- Hinz F. (1989) Classes of picture languages that cannot be distinguished in the chain code concept and deletion of redundant retreats. In: Monien B., Cori R. (eds) STACS 89. STACS 1989. Lecture Notes in Computer Science, vol 349. Springer, Berlin, Heidelberg
Maurer, Rozenberg and Welzl showed that every recursively enumerable chain code picture language is described by a context-sensitive string language. We show that every regular picture language is described star-free and every context-free picture language is described deterministic. We investigate closure properties of language classes concerning deletion of redundant retreats and thereby establish a normal form for regular picture languages.
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