We show that free products of finitely generated and residually p-finite nilpotent groups, amalgamating p-closed central subgroups are residually p-finite. As a consequence, we are able to show that generalized free products of residually p-finite abelian groups are residually p-finite if the amalgamated subgroup is closed in the pro-p topology on each of the factors.

A proof of freeness of the commutator subgroup of the fundamental group of a smooth irreducible affine curve over a countable algebraically closed field of nonzero characteristic. A description of the abelianizations of the fundamental groups of affine curves over an algebraically closed field of nonzero characteristic is also given.

Let [Formula: see text] be a class of finite groups closed under taking subgroups, homomorphic images and extensions. It is known that if normal subgroup group then the image an text]-maximal in not, general, text]. We say reduction text]-theorem holds for if, every extension (i.e. contains as subgroup), number conjugacy classes subgroups same. The implies In this paper, we prove only all are c...

We show that the quasiconvex subgroups in doubles of certain negatively curved groups are closed in the profinite topology. This allows us to construct the first known large family of hyperbolic 3-manifolds such that any finitely generated subgroup of the fundamental group of any member of the family is closed in the profinite topology.

The sets of closed and closed-normal subgroups of a profinite group carry a natural profinite topology. Through a combination of algebraic and topological methods the size of these subgroup spaces is calculated, and the spaces partially classified up to homeomorphism.

The Mackey–Zimmer theorem classifies ergodic group extensions $X$ of a measure-preserving system $Y$ by compact $K$, showing that such are isomorphic to skew-product $X \equiv Y \rtimes _\rho H$ for some closed subgroup $

A closed subgroup $H$ of a locally compact group $G$ is confined if the closure conjugacy class in Chabauty space does not contain trivial subgroup. We establish dynamical criterion on action totally disconnected $X$ ensuring that no relatively amenable can be confined. This property equivalent to fact its Furstenberg boundary free. Our applies Neretin groups. deduce each has two inequivalent i...

We provide a new construction of the strongly regular graphs associated with the two sporadic simple groups M22 and HS. Further, we give some new constructions of other known strongly regular graphs by taking the orbits of a certain subgroup of M22 on the planes of the Hermitian variety H(5, 4). These geometric constructions can be used to produce cap codes with large parameters and automorphis...

This paper gives decidable conditions for when a nitely generated subgroup of a free group is the fundamental group of a Sch utzenberger automaton corresponding to a monoid presentation of an inverse monoid. Also, generalizations are given to speciic types of inverse monoids as well as to monoids which are \nearly inverse." This result has applications to computing membership for inverse monoid...

in this paper, the concept of fuzzy convex subgroup (resp. fuzzy convex lattice-ordered subgroup) of an ordered group (resp. lattice-ordered group) is introduced and some properties, characterizations and related results are given. also, the fuzzy convex subgroup (resp. fuzzy convex lattice-ordered subgroup) generated by a fuzzy subgroup (resp. fuzzy subsemigroup) is characterized. furthermore,...