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Dear forum,

Robert Scarth asked

When I ask GAP for a presentation of a subgroup H, of G, say it

returns a presentation on generators _x<i>. For any i, can GAP give

me an expression for _x<i> in terms of the generators of G?

In fact, GAP 3.4.3 cannot do this.

However, the new release GAP 3.4.4 (which has been announced

to be available just one week ago) has been extended such

that now, whenever you call the function PresentationSubgroup,

the resulting presentation record P will involve an additional

component P.primaryGeneratorWords which provides words in the

generators of G for all primary generators occurring in the

subgroup presentation.

The new facilities are described in the chapter on Finitely

Presented Groups in version 3.4.4 of the GAP manual.

My suggestion is that you should try to get hands on the new

version as soon as possible. I assume that will solve your

problem.

Best regards,

Volkmar Felsch, Aachen

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