On a New Characterization of Demuskin Groups.
On a Non-Abelian Variety of Groups which are Symmetric Algebras.
On a Problem of Fox.
On a problem of Freudenthal's
On a problem on explicit embeddings of the group .
On a property of groups with coverings.
On a question of Deaconescu about automorphisms
On a question of Deaconescu about automorphisms. - II
On a question of Deaconescu about automorphisms. - III
On a result of G. Baumslag
On a semigroup theoretic generalization of the Kaluznin Krasner Theorem and normal extensions of inverse semigroups.
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 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 Amalgamated Products of Profinite Groups.
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 equivalence of fuzzy subgroups. III.