Derivatives of Regular Expressions
Journal of the ACM (JACM)
On Decompositions of Regular Events
Journal of the ACM (JACM)
A Purely Homomorphic Characterization of Recursively Enumerable Sets
Journal of the ACM (JACM)
Free groups and regular expressions
STOC '69 Proceedings of the first annual ACM symposium on Theory of computing
Determination of finite automata accepting subregular languages
Theoretical Computer Science
Star height of certain families of regular events
Journal of Computer and System Sciences
General properties of star height of regular events
Journal of Computer and System Sciences
Properties of code events and homomorphisms over regular events
Journal of Computer and System Sciences
Inverse star, borders, and palstars
Information Processing Letters
Nondeterministic state complexity of star-free languages
CIAA'11 Proceedings of the 16th international conference on Implementation and application of automata
Nondeterministic state complexity of star-free languages
Theoretical Computer Science
On inverse operations and their descriptional complexity
DCFS'12 Proceedings of the 14th international conference on Descriptional Complexity of Formal Systems
The inclusion problem for regular expressions
Journal of Computer and System Sciences
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A regular event W is a star event if there exists another event V such that W = V*. In that case, V is called a root of W. It is shown that every star event has a unique minimum root, which is contained in every other root. An algorithm for finding the minimum root of a regular event is presented, and the root is shown to be regular. The results have applications to languages, codes, canonical forms for regular expressions, simplification of expressions, decomposition of sequential machines, and semigroup theory.