> ^ From:

> ^ Subject:

I tried to compute a presentation of the normal closure of

the subgroup generated by the commutator of the two generators of a free

group on two letters with gap, and it appears to be enumerating something

which is infinite.

Below is a transcript of what I tried to do.

This is my very first attempt at using gap, so I very well may be doing

something silly...

Any help will be wellcome.

Thanx,

Mariano Suarez Alvarez

-----------

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

gap> E := F / [] ;;

gap> a := E.1 ;; b := E.2 ;;

gap> R := Subgroup( E, [a*b*a^-1*b^-1] ) ;;

gap> PresentationNormalClosure( E, R ) ;

Error, the coset enumeration has defined more than 64000 cosets:

type 'return;' if you want to continue with a new limit of 128000 cosets,

type 'quit;' if you want to quit the coset enumeration,

type 'maxlimit := 0; return;' in order to continue without a limit,

in

CosetTableFpGroup( F, TrivialSubgroup( F ) ) called from

PresentationNormalClosure( E, R ) called from

main loop

brk> return ;

Error, the coset enumeration has defined more than 128000 cosets:

type 'return;' if you want to continue with a new limit of 256000 cosets,

type 'quit;' if you want to quit the coset enumeration,

type 'maxlimit := 0; return;' in order to continue without a limit,

in

CosetTableFpGroup( F, TrivialSubgroup( F ) ) called from

PresentationNormalClosure( E, R ) called from

main loop

brk>

gap>

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