Identification of unions of languages drawn from an identifiable class
COLT '89 Proceedings of the second annual workshop on Computational learning theory
Decision problems for patterns
Journal of Computer and System Sciences
Handbook of formal languages, vol. 1
Handbook of Formal Languages
Polynomial Time Inference of Extended Regular Pattern Languages
Proceedings of RIMS Symposium on Software Science and Engineering
Developments from enquiries into the learnability of the pattern languages from positive data
Theoretical Computer Science
Theoretical Computer Science
Existence and Nonexistence of Descriptive Patterns
DLT '09 Proceedings of the 13th International Conference on Developments in Language Theory
Bad news on decision problems for patterns
Information and Computation
Inferring descriptive generalisations of formal languages
Journal of Computer and System Sciences
Hi-index | 5.23 |
In the present paper, we study the existence of descriptive patterns, i.e. patterns that cover all words in a given set through morphisms and that are optimal in terms of revealing commonalities of these words. Our main result shows that if patterns may be mapped to words by arbitrary morphisms, then there exist infinite sets of words that do not have a descriptive pattern. This answers a question posed by Jiang et al. (Pattern languages with and without erasing, International Journal of Computer Mathematics 50 (1994)). Since the problem of whether a pattern is descriptive depends on the inclusion relation of so-called pattern languages, our technical considerations lead to a number of deep insights into the inclusion problem for and the topology of the class of terminal-free E-pattern languages.