Abstract
In this note, we show that if \({\fancyscript N}\)is a proper subfactor of a factor ℳ of type II1 with finite Jones index, then there is a maximal abelian self–adjoint subalgebra (masa) \({\fancyscript A}\)of \({\fancyscript N}\)that is not a masa in ℳ. Popa showed that there is a proper subfactor ℛ0 of the hyperfinite type II1 factor ℛ such that each masa in ℛ0 is also a masa in ℛ. We shall give a detailed proof of Popa's result.
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This work is supported by the National Natural Science Foundation of China (10301004)
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Wang, L.G. On Maximal Abelian Self–adjoint Subalgebras of Factors of Type II1 . Acta Math Sinica 21, 569–576 (2005). https://doi.org/10.1007/s10114-004-0460-x
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DOI: https://doi.org/10.1007/s10114-004-0460-x