On a subgroup of the affine Weyl group .
On a theorem of Baumslag, Dyer and Heller linking group theory and topology
On a theorem of Schur.
On absolutely simple locally finite groups
On absolutely-nilpotent of class groups
A group in a variety is said to be absolutely-, and we write , if central extensions by are again in . Absolutely-abelian groups have been classified by F. R. Beyl. In this paper we concentrate upon the class of absolutely-nilpotent of class groups. We prove some closure properties of the class and we show that every nilpotent of class group can be embedded in an -gvoup. We describe all metacyclic -groups and we characterize -generator and infinite -generator -groups. Finally...
On adjoining units to hyper-archimedean -groups
On algebraic Anosov diffeomorphisms on nilmanifolds.
On almost finitely generated nilpotent groups.
On almost normal subgroups of supersoluble groups
Un sottogruppo di un gruppo si dice «almost normal» se ha soltanto un numero finito di coniugati in , e ovviamente l'insieme costituito dai sottogruppi almost normal di è un sottoreticolo del reticolo di tutti i sottogruppi di . In questo articolo vengono studiati gli isomorfismi tra reticoli di sottogruppi almost normal, provando in particolare che se è un gruppo supersolubile e è un gruppo FC-risolubile tale che i reticoli e sono isomorfi, allora anche è supersolubile, e...
On an algorithm to decide whether a free group is a free factor of another
We revisit the problem of deciding whether a finitely generated subgroup is a free factor of a given free group . Known algorithms solve this problem in time polynomial in the sum of the lengths of the generators of and exponential in the rank of . We show that the latter dependency can be made exponential in the rank difference rank - rank, which often makes a significant change.
On an algorithm to decide whether a free group is a free factor of another
We revisit the problem of deciding whether a finitely generated subgroup H is a free factor of a given free group F. Known algorithms solve this problem in time polynomial in the sum of the lengths of the generators of H and exponential in the rank of F. We show that the latter dependency can be made exponential in the rank difference rank(F) - rank(H), which often makes a significant change.
On an open problem of Green and Losonczy: exact enumeration of freely braided permutations.
On aspherical presentations of groups.
On asymptotic dimension of groups.
On automorphisms fixing subnormal subgroups of soluble groups
The group of all automorphisms leaving invariant every subnormal subgroup of the group is studied. In particular it is proved that is metabelian if is soluble, and that is either finite or abelian if is polycyclic.
On Bimorphisms and Quadratic Forms on Groups
On Bimorphisms and Quadratic Forms on Groups. (Short Communications).
On Cancellations in HNN-Groups.
On central extensions of mapping class groups.
On centralizers of elements of groups acting on trees with inversions.