A Continuous Path of Singular Masas in the Hyperfinite II_1 Factor

dc.creatorSinclair, Allan
dc.creatorWhite, Stuart
dc.date2006-02-08
dc.date.accessioned2026-07-07T07:52:19Z
dc.date.available2026-07-07T07:52:19Z
dc.descriptionUsing methods of R.J.Tauer we exhibit an uncountable family of singular masas in the hyperfinite $\textrm{II}_1$ factor $\R$ all with Pukánszky invariant $\{1\}$, no pair of which are conjugate by an automorphism of $R$. This is done by introducing an invariant $Γ(A)$ for a masa $A$ in a \IIi factor $N$ as the maximal size of a projection $e\in A$ for which $A e$ contains non-trivial centralising sequences for $eN e$. The masas produced give rise to a continuous map from the interval $[0,1]$ into the singular masas in $\R$ equiped with the $d_{\infty,2}$-metric. A result is also given showing that the Pukánszky invariant is $d_{\infty,2}$-upper semi-continuous. As a consequence, the sets of masas with Pukánszky invariant $\{n\}$ are all closed.
dc.description18 pages
dc.identifierhttps://arxiv.org/abs/math/0602155
dc.identifierhttp://arxiv.org/abs/math/0602155
dc.identifierJ. London Math. Soc. (2) 75 (2007) 243-254
dc.identifierdoi:10.1112/jlms/jdl019
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/125837
dc.subjectOperator Algebras
dc.subject46L10
dc.titleA Continuous Path of Singular Masas in the Hyperfinite II_1 Factor
dc.typetext

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