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Dear Forum,

Let g:=Group(....). Is there any natural way to avoid calling a procedure

checking whether h:=Subgroup(g,[...]) is indeed a subgroup in the

moment of creating h?

As we were told, this checking might be rather expensive if the

generators of h does not form a subset of g.generators.

Suppose one knows that the generators of h are words in g.generators.

Then a strange way to create h fast is to add these words into

g.generators.

Can it be avoided?

For instance, if g is a matrix group, there are no efficient ways to

check that h<=g, so in fact I several times ran into this problem,

when I created a subgroup of a matrix group, and

gave up without understanding what went wrong.

Regards, Dima

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