On real-time word problems
by Derek Holt and Claas Röver
Keywords
word problems of groups, real-time languages
Abstract
We prove that the word problem of
the direct product of two free groups of rank two can be recognised
by a two-tape real-time but not by a one-tape real-time Turing machine.
We also prove that the Baumslag-Solitar groups B(1,r) have 5-tape
real-time word problem for all non-zero r.
This is published in J. London Math. Soc. (2) 67 (2003), no. 2, 289-301
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