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Average-case complexity and decision problems in group theory

Ilya Kapovich·Alexei Myasnikov·Paul Schupp·Vladimir Shpilrain
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Abstract

We investigate the average-case complexity of decision problems for finitely generated groups, in particular the word and membership problems. Using our recent results on ``generic-case complexity'' we show that if a finitely generated group $G$ has the word problem solvable in subexponential time and has a subgroup of finite index which possesses a non-elementary word-hyperbolic quotient group, then the average-case complexity of the word problem for $G$ is linear time, uniformly with respect to the collection of all length-invariant measures on $G$. For example, the result applies to all braid groups $B_n$.

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Ilya Kapovich, Alexei Myasnikov, Paul Schupp, Vladimir Shpilrain. 2002-08-22. Average-case complexity and decision problems in group theory. https://arxiv.org/abs/math/0206273

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