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On the learnability of E-pattern languages over small alphabets
journal contribution
posted on 2008-07-09, 09:02 authored by Daniel ReidenbachThis paper deals with two well discussed, but largely open
problems on E-pattern languages, also known as extended or erasing
pattern languages: primarily, the learnability in Gold’s learning model
and, secondarily, the decidability of the equivalence. As the main result,
we show that the full class of E-pattern languages is not inferrable from
positive data if the corresponding terminal alphabet consists of exactly
three or of exactly four letters – an insight that remarkably contrasts
with the recent positive finding on the learnability of the subclass of
terminal-free E-pattern languages for these alphabets. As a side-effect of
our reasoning thereon, we reveal some particular example patterns that
disprove a conjecture of Ohlebusch and Ukkonen (Theoretical Computer
Science 186, 1997) on the decidability of the equivalence of E-pattern
languages.
History
School
- Science
Department
- Computer Science
Citation
REIDENBACH, D., 2004. On the learnability of E-pattern languages over small alphabets. Lecture Notes in Computer Science, 3120, pp. 140-154Publisher
© Springer-VerlagPublication date
2004Notes
This is a journal article. It was published in Lecture Notes in Computer Science [© Springer Verlag] and the definitive version is available at: www.springerlink.comISBN
9783540222828ISSN
0302-9743;1611-3349Language
- en