Cyclic quasinormal subgroups of arbitrary groups
The original version of the article was published in Central European Journal of Mathematics, 2011, 9(4), 915–921, DOI: 10.2478/s11533-011-0029-8. Unfortunately, the original version of this article contains a mistake: Lemma 2.1 (2) is not true. We correct Lemma 2.2 (2) and Theorem 1.1 in our paper where this lemma was used.
Suppose G is a finite group and H is a subgroup of G. H is called weakly s-permutably embedded in G if there are a subnormal subgroup T of G and an s-permutably embedded subgroup of G contained in H such that G = HT and ; H is called weakly s-supplemented in G if there is a subgroup T of G such that G = HT and , where is the subgroup of H generated by all those subgroups of H which are s-permutable in G. We investigate the influence of the existence of s-permutably embedded and weakly s-supplemented...
Un sottogruppo di un gruppo è chiamato seminormale se è permutabile con ogni sottogruppo di un conveniente supplemento di in (X. SU [2]). Nel nostro lavoro vengono caratterizzati tutti i gruppi finiti in cui ogni sottogruppo di Sylow è seminormale. Viene anche dimostrato che ogni -gruppo finito ( primo dispari) in cui ogni sottogruppo di Sylow è seminormale gode della proprietà che tutti i suoi sottogruppi sono a due a due permutabili.
A subgroup H of a group G is said to permute with a subgroup K of G if HK is a subgroup of G. H is said to be permutable (resp. S-permutable) if it permutes with all the subgroups (resp. Sylow subgroups) of G. Finite groups in which permutability (resp. S-permutability) is a transitive relation are called PT-groups (resp. PST-groups). PT-, PST- and T-groups, or groups in which normality is transitive, have been extensively studied and characterised. Kaplan [Kaplan G., On T-groups, supersolvable...
A finite solvable group G is called an X-group if the subnormal subgroups of G permute with all the system normalizers of G. It is our purpose here to determine some of the properties of X-groups. Subgroups and quotient groups of X-groups are X-groups. Let M and N be normal subgroups of a group G of relatively prime order. If G/M and G/N are X-groups, then G is also an X-group. Let the nilpotent residual L of G be abelian. Then G is an X-group if and only if G acts by conjugation on L as a group...