Introduction to computer theory (revised ed.)
Introduction to computer theory (revised ed.)
Journal of Symbolic Computation - Special issue on computational group theory: part 2
Using rewriting systems to compute left Kan extensions and induced actions of categories
Journal of Symbolic Computation
Computing Double Coset Representatives for the Generation of Solvable Groups
EUROCAM '82 Proceedings of the European Computer Algebra Conference on Computer Algebra
Double cosets and searching small groups
SYMSAC '81 Proceedings of the fourth ACM symposium on Symbolic and algebraic computation
A rewriting alternative to Reidemeister-Schreier
RTA'03 Proceedings of the 14th international conference on Rewriting techniques and applications
On properties not inherited by monoids from their Schützenberger groups
Information and Computation
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In this paper we show how string rewriting methods can be applied to give a new method of computing double cosets. Previous methods for double cosets were enumerative and thus restricted to finite examples. Our rewriting methods do not suffer this restriction and we present some examples of infinite double coset systems which can now easily be solved using our approach. Even when both enumerative and rewriting techniques are present, our rewriting methods will be competitive because they (i) do not require the preliminary calculation of cosets; and (ii) as with single coset problems, there are many examples for which rewriting is more effective than enumeration. Automata provide the means for identifying expressions for normal forms in infinite situations and we show how they may be constructed in this setting. Further, related results on logged string rewriting for monoid presentations are exploited to show how witnesses for the computations can be provided and how information about the subgroups and the relations between them can be extracted. Finally, we discuss how the double coset problem is a special case of the problem of computing induced actions of categories which demonstrates that our rewriting methods are applicable to a much wider class of problems than just the double coset problem.