Prüfer and Dedekind monoids.
Chevalley’s theorem states that every smooth connected algebraic group over a perfect field is an extension of an abelian variety by a smooth connected affine group. That fails when the base field is not perfect. We define a pseudo-abelian variety over an arbitrary field to be a smooth connected -group in which every smooth connected affine normal -subgroup is trivial. This gives a new point of view on the classification of algebraic groups: every smooth connected group over a field is an extension...
We show that in a weak commutative inverse property loop, such as a Bruck loop, if is a right [left] pseudoautomorphism with companion , then [] must lie in the left nucleus. In particular, for any such loop with trivial left nucleus, every right pseudoautomorphism is an automorphism and if the squaring map is a permutation, then every left pseudoautomorphism is an automorphism as well. We also show that every pseudoautomorphism of a commutative inverse property loop is an automorphism, generalizing...
Let be an infinite cardinal. Set , define for every , take as the first cardinal with , and put . If is a torsion-free group of cardinality at least and is its subgroup such that is torsion and , then contains a non-zero subgroup pure in . This generalizes the result from a previous paper dealing with -primary.