Did you try: Size(G);
That should, if it is the trivial group, give you the answer "1". If it isn't, it will not stop running. Since it is not decidable whether a presentation presents the trivial group there is not more you can hope for. Best wishes Stephan Rosebrock Am Sa, 15.08.2009, 19:15, schrieb Daniel Ruberman: > Does anyone have any practical advice on showing that a finite > presentation that one suspects to be for the trivial group, in fact is > the trivial group? The initial presentation of the group (G below) > has 8 generators and 18 relations of total length 88. After applying > the commands > gap> P:=PresentationFpGroup(G); > <presentation with 8 gens and 18 rels of total length 88> > gap> TzGoGo(P); > #I there are 4 generators and 14 relators of total length 183 > #I there are 4 generators and 14 relators of total length 181 > > there doesn't seem to be much simplification! > > Obvious tests, such as AbelianInvariants(G) or running > LowIndexSubgroupsFpGroup(G,8); > don't distinguish G from the trivial group. > > Any suggestions would be gratefully accepted; this could of course > include calculations doable in GAP or otherwise. > > Thanks, > Daniel Ruberman > > Department of Mathematics > Brandeis University > Waltham, MA 02454 > http://www.brandeis.edu/~ruberman/ > > _______________________________________________ > Forum mailing list > Forum@mail.gap-system.org > http://mail.gap-system.org/mailman/listinfo/forum > ********************************************************* * Dr. Stephan Rosebrock * * * * Paedagogische Hochschule Karlsruhe * * Bismarckstr. 10 * * 76133 Karlsruhe * * Deutschland / Germany * * * * e-mail: rosebr...@ph-karlsruhe.de * * home page: http://www.rosebrock.ph-karlsruhe.de/ * * * * Tel: 0721-925-4275 * * Fax: 0721-925-4249 * ********************************************************* _______________________________________________ Forum mailing list Forum@mail.gap-system.org http://mail.gap-system.org/mailman/listinfo/forum
