Groups associated to -factors
arXiv:1205.2862 · doi:10.1016/j.jfa.2012.11.003
Abstract
We extend recent work of the first named author, constructing a natural Hom semigroup associated to any pair of II-factors. This semigroup always satisfies cancelation, hence embeds into its Grothendieck group. When the target is an ultraproduct of a McDuff factor (e.g., ), this Grothendieck group turns out to carry a natural vector space structure; in fact, it is a Banach space with natural actions of outer automorphism groups.