hello world,
maybe i'm missing something, but the following seems strange to me:

gap> F := FreeGroup("a","b"); G := F / [F.1^3, F.2^3];
# first term in lower central series
gap> L := [G];
# second term
gap> L[2] := CommutatorSubgroup(L[1],G);
Error the coset enumeration has defined more than 256000 cosets:
<snip snip>
gap> L[2] := DerivedSubgroup(G); # hurray!
gap> L[3] := CommutatorSubgroup(L[2],G);
Error the coset enumeration has defined more than 256000 cosets:
# and no way to obtain it...

so: since these L[n] are finitely generated, couldn't gap be able to
compute them? (and then, provide their index, etc)
and: why does derivedsubgroup() work, if there is an objection to
working with
infinite groups?

thanks,
laurent
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