Department of Mathematics, University of California, Irvine, California 92697 ; Department of Mathematics, University of Wisconsin, Madison, Wisconsin 53706
Abstract:
We answer a long-standing open question by proving in ordinary set theory, ZFC, that the Kaplansky test problems have negative answers for -separable abelian groups of cardinality . In fact, there is an -separable abelian group such that is isomorphic to but not to . We also derive some relevant information about the endomorphism ring of .