English

Homotopy of vector states

Operator Algebras 2007-05-23 v1

Abstract

Let BB be a C^*-algebra and XX a C^* Hilbert BB-module. If pBp\in B is a projection, denote by Sp={xX:<x,x>=p}S_p =\{x\in X : < x,x> =p\}, the pp-sphere of XX. For ϕ\phi a state of BB with support pp in BB and xSpx\in S_p, consider the state ϕx\phi_x of LB(X)L_B(X) given by ϕx(t)=ϕ(<x,t(x)>)\phi_x(t)= \phi(< x,t(x)>). In this paper we study certain sets associated to these states, and examine their topologic properties. As an application of these techniques, we prove that the space of states of the hyperfinite II1_1 factor R0R_0, with support equivalent to a given projection pR0p\in R_0, regarded with the norm topology (of the conjugate space of R0R_0), has trivial homotopy groups of all orders. The same holds for the space Sp(R0)={vR0:vv=p}R0 S_p(R_0)=\{v\in R_0:v^*v=p\}\subset R_0 of partial isometries with initial space pp, regarded with the ultraweak topology.

Keywords

Cite

@article{arxiv.math/0008144,
  title  = {Homotopy of vector states},
  author = {Esteban Andruchow and Alejandro Varela},
  journal= {arXiv preprint arXiv:math/0008144},
  year   = {2007}
}

Comments

23 pages, Latex

R2 v1 2026-07-22T16:34:16.076Z