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Title: Extended regular expressions: succinctness and decidability
Authors: Freydenberger, Dominik D.
Issue Date: 2011
Publisher: Schloss Dagstuhl – Leibniz-Zentrum für Informatik, Dagstuhl Publishing, Germany
Citation: FREYDENBERGER, D.D., 2011. Extended regular expressions: succinctness and decidability. IN: Schwentick, T. and Dürr, C. (eds). Leibniz International Proceedings in Informatics: 28th Symposium on Theoretical Aspects of Computer Science (STACS’11), Dortmund, Germany, 10th-12th March, pp.507-518
Series/Report no.: Leibniz International Proceedings in Informatics (LIPIcs); 9
Abstract: Most modern implementations of regular expression engines allow the use of variables (also called back references). The resulting extended regular expressions (which, in the literature, are also called practical regular expressions, rewbr, or regex) are able to express non-regular languages. The present paper demonstrates that extended regular-expressions cannot be minimized effectively (neither with respect to length, nor number of variables), and that the tradeoff in size between extended and "classical" regular expressions is not bounded by any recursive function. In addition to this, we prove the undecidability of several decision problems (universality, equivalence, inclusion, regularity, and cofiniteness) for extended regular expressions. Furthermore, we show that all these results hold even if the extended regular expressions contain only a single variable. © Dominik D. Freydenberger.
Description: This conference paper was presented at the 28th Symposium on Theoretical Aspects of Computer Science (STACS’11).
Version: Published
DOI: 10.4230/LIPIcs.STACS.2011.507
URI: https://dspace.lboro.ac.uk/2134/26390
Publisher Link: http://dx.doi.org/10.4230/LIPIcs.STACS.2011.507
ISBN: 9783939897255
ISSN: 1868-8969
Appears in Collections:Conference Papers and Presentations (Computer Science)

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