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.

We study the geometry of compact Lorentzian manifolds that admit a somewhere timelike Killing vector field, and whose isometry group has infinitely many connected components. Up to a finite cover, such manifolds are products (or amalgamated products) of a flat Lorentzian torus and a compact Riemannian (resp., lightlike) manifold.

The polynomial automorphisms of the affine plane over a field K form a group which has the structure of an amalgamated free product. This well-known algebraic structure can be used to determine some key results about the symmetry and reversing symmetry groups of a given polynomial automorphism.

We describe a general technique for embedding certain amalgamated products into direct products. This technique provides us with a way of constructing a host of finitely presented subgroups of automatic groups which are not even asynchronously automatic. We can also arrange that such subgroups satisfy, at best, an exponential isoperimetric inequality.

A literature review was performed to look at the interactions between alcohol and methotrexate in non-malignant disease. The evidence from research into psoriasis and inflammatory arthritis, and an overview of international and national guidelines, was amalgamated into some consensus recommendations.

In this paper we study residual solvability of the amalgamated product of two finitely generated free groups, in the case of doubles. We find conditions where this kind of structure is residually solvable, and show that in general this is not the case. However this kind of structure is always meta-residually-solvable.

We construct three groups Λ1, Λ2, Λ3, which can all be decomposed as amalgamated products F9∗F81F9 and have very few normal subgroups of finite or infinite index. Concretely, Λ1 is a simple group, Λ2 is not simple but has no non-trivial normal subgroup of infinite index, and Λ3 is not simple but has no proper subgroup of finite index.

We prove that any Lie subgroup G (with finitely many connected components) of an infinite-dimensional topological group which is amalgamated product two closed subgroups can be conjugated to one factor. apply this result classify actions on Danielewski surfaces by elements the overshear (up conjugation).