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hello again,

i ran in a few new other problems with gap, which are:

i cannot define a group algebra over an infinite non-free group:

gap> G := FreeGroup("a","b");

<free group on the generators [ a, b ]>

gap> GroupRing(GF(2),G);

<algebra-with-one over GF(2), with 4 generators>

gap> G := G / [Comm(G.1,G.2)];

<fp group on the generators [ a, b ]>

gap> GroupRing(GF(2),G);

Error the coset enumeration has defined more than 256000 cosets:

and also i can't run ReducedConfluentRewritingSystem on a f.p. group --

gap wants a f.p. semigroup. i would have thought AsSemigroup(G) would

work, but alas not.

concerning coset enumeration, couldn't it be possible to set up a flag in

a group structure that the group is infinite, so that gap does not attempt

element or coset enumeration, but rather answers by an error message?

cheers all,

laurent

[p.s. to derek holt: yes, i saw your message. it gave me courage to clog

gap-forum with my problem, since it obviously is something of great

interest]

``a theorem is a device for turning mathematicians into coffee'' -- not Erdös E-Mail: mailto:laurent.barth0ldi@math.unige.ch (replace 0 by o) S-Mail: Laurent Bartholdi, 15 Bvd de la Cluse, 1205 Genève, Switzerland Office: #610B, 2-4 Rue du Lièvre, Case Postale 240, 1211 Genève 24, Switzerland Phones: +41 78 7480012 (mobile) +41 22 3280012 (home) +41 22 3095437 (office)

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