Groups that do and do not have growing context-sensitive wordproblem
Derek F. Holt, Sarah Rees and Michael Shapiro
Keywords
word problem, formal languages, grammars, Dehn algorithm, growing context-sensitive
Status
published in Int. J. Alg. Comput. 18 (2008) 1179-1191.
Abstract
We prove that a group has word problem that is a growing
context-sensitive language precisely if its word problem can be solved
using a non-deterministic Cannon's algorithm (the deterministic
algorithms being defined by Goodman and Shapiro in
\cite{GoodmanShapiro}). We generalise results of \cite{GoodmanShapiro}
to find many examples of groups not admitting non-deterministic
Cannon's algorithms. This adds to the examples of
Kambites and Otto in~\cite{KambitesOtto} of groups
separating context-sensitive and growing context-sensitive word problems,
and provides a new language-theoretic separation result.
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