A 30-article volume, introducing an active and attractive part of algebra that has gained much from its position at the crossroads of mathematics over the years. The papers stimulate the reader to consider and actively investigate the topics and problems they contain.

Inhalt

Ross Allen Beaumont (In Memoriam).- Modular group algebras and simply presented groups.- Abelian automorphism groups of countable rank.- Transitivity and full transitivity over subgroups of abelian p-groups.- Subgroups of p5-bounded groups.- Groups acting on modules.- Some mixed abelian groups as modules over the ring of pseudo-rational numbers.- The Baer-Kaplansky theorem for direct sums of self-small mixed groups.- Finite rank Butler groups with small typesets.- Normal forms of matrices with applications to almost completely decomposable groups.- Admissible matrices as base changes of B(1)-groups: a realizing algorithm.- Butler modules over 1-dimensional Noetherian domains.- Completely decomposable summands of almost completely decomposable groups.- Some matrix rings associated with ACD groups.- Stacked bases for a pair of homogeneous completely decomposable groups with bounded quotient.- Separability conditions for vector R-modules.- Almost disjoint pure subgroups of the Baer-Specker group.- Abelian groups mapping onto their endomorphism rings.- Purity and Reid's theorem.- Basic subgroups and a freeness criterion for torsion-free abelian groups.- Absolutely rigid systems and absolutely indecomposable groups.- Around nonclassifiability for countable torsion free abelian groups.- On the compact-open topology of Ext(C,A).- Direct decompositions of LCA groups.- Realizing automorphism groups of metabelian groups.- On the class semigroups of Prüfer domains.- Uniform modules, ?-invariants, and Ziegler spectra of regular rings.- Locally simple objects.- On purely extending modules.- The number of submodules.