The factor-valued pinching conjecture for type-II-infinity and type-III factors

Let R{\mathfrak{R}} be a type-II{\mathrm{II}}_{\infty} or type-III{\mathrm{III}} factor, let WeR(A)W_e^{\mathfrak{R}}(A) denote its essential numerical range, and let D{\mathcal{D}} be the set used in the preceding pinching results. An isometric decomposition of R{\mathfrak{R}} is a sequence {Vi}i=1\{V_i\}_{i=1}^{\infty} of isometries in R{\mathfrak{R}} such that

i=1ViVi=I.\sum_{i=1}^{\infty}V_iV_i^*=I.

Factor-valued pinching conjecture. If ARA\in{\mathfrak{R}} satisfies WeR(A)DW_e^{\mathfrak{R}}(A)\supset{\mathcal{D}} and {Xi}i=1R\{X_i\}_{i=1}^{\infty}\subset{\mathfrak{R}} satisfies supiXi<1\sup_i\|X_i\|<1, then there exists an isometric decomposition {Vi}i=1\{V_i\}_{i=1}^{\infty} of R{\mathfrak{R}} such that

ViAXi=XiV_i^*AX_i=X_i

for all ii. The conjecture proposes that the pinching theorem extends from L(H){\mathrm{L}}({\mathcal{H}}) to these von Neumann factors, giving affirmative answers to the preceding extension questions; the source indicates that this is suggested by related decompositions of positive operators, but does not establish the factor version.

Sources & referencesView supporting material

Primary source

Jean-Christophe Bourin and Eun-Young Lee, “Pinchings and Positive linear maps”, arXiv:1505.02341 (2015).

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