an:06101632
Zbl 1370.68211
Okhotin, Alexander
Non-erasing variants of the Chomsky-Sch??tzenberger theorem
EN
Yen, Hsu-Chun (ed.) et al., Developments in language theory. 16th international conference, DLT 2012, Taipei, Taiwan, August 14--17, 2012. Proceedings. Berlin: Springer (ISBN 978-3-642-31652-4/pbk). Lecture Notes in Computer Science 7410, 121-129 (2012).
2012
a
68Q70
Summary: The famous theorem by \textit{N. Chomsky} and \textit{M. P. Sch??tzenberger} [in: Computer programming and formal systems, Stud. Logic Found. Math., 118--161 (1963; Zbl 0148.00804)] states that every context-free language is representable as \(h(D _{k } \cap R)\), where \(D _{k }\) is the Dyck language over \(k \geqslant 1\) pairs of brackets, \(R\) is a regular language and \(h\) is a homomorphism. This paper demonstrates that one can use a non-erasing homomorphism in this characterization, as long as the language contains no one-symbol strings. If the Dyck language is augmented with neutral symbols, the characterization holds for every context-free language using a letter-to-letter homomorphism.
For the entire collection see [Zbl 1248.68052].
Zbl 0148.00804