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 := CommutatorSubgroup(L,G); Error the coset enumeration has defined more than 256000 cosets: <snip snip> gap> L := DerivedSubgroup(G); # hurray! gap> L := CommutatorSubgroup(L,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
thanks, laurent -- E-Mail: mailto:firstname.lastname@example.org (replace 0 by o) S-Mail: Laurent Bartholdi c/o Grigorchuk, 11 Rhov Etsel, Jerusalem Office: #304, Einstein Institute of Math., Hebrew University, 91904 Jerusalem Phones: +41 78 7480012 (mobile) +972 2 5815081 (home) +972 2 6586816 (office)