hello world,
i run into a problem with gap, which is:

G := FreeGroup("a","b","c","d");
ga := G.1; gb := G.2; gc := G.3; gd := G.4;
H := Subgroup(G,[ga^2,gb,gc,gd,gb^ga,gc^ga,gd^ga]);
phi := [GroupHomomorphismByImages(H,G,[ga^2,gb,gc,gd,gb^ga,gc^ga,gd^ga],
[Identity(G),ga,ga,Identity(G),gc,gd,gb]);

ap> Image(phi,H.1);
<identity ...>
[this is ok]
gap> Image(phi,H.1^2);
[endless loop, instead of <identity ...>]
gap> Image(phi,H.1*H.3);
fail
[instead of a]
gap>

i know the problem can be tough to express a subgroup element as a word
in some fixed generators, but H has index 2, so the task surely cannot
be so difficult?
thanks all,
laurent

``a theorem is a device for turning mathematicians into coffee'' -- not Erdös
E-Mail: mailto:laurent.barth0ldi@math.unige.ch (replace 0 by o)
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