analysis / Operator algebras: paving and maximal abelian subalgebras

The Popa-Vaes paving conjecture over arbitrary maximal abelian subalgebras: strong-operator, approximation and quadratic paving

Quadratic paper, Theorem 1.1: for 0<ε<10<\varepsilon<1 and rε≤5×108ε−2r_\varepsilon\le5\times10^8\varepsilon^{-2}, every self-adjoint xx in any von Neumann algebra MM is (ε,rε)(\varepsilon,r_\varepsilon) so-pavable over every MASA A⊆MA\subseteq M, with no separability or conditional expectation assumed; corollary: quadratic norm paving in Ocneanu ultrapowers of expected countably decomposable MASAs. Approximation paper, Theorem 1.1: every self-adjoint xx is a strong limit of self-adjoint yy with ∥y∥≤3∥x∥\|y\|\le3\|x\|, each norm-pavable to error ε∥y∥\varepsilon\|y\| with at most Cε−6C\varepsilon^{-6} projections. Not shown: norm paving of the original operator (false in general), optimal numerical constants, or a quadratic rate for approximation paving.

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analysisSep 25, 2026Significance 20/100Registry: unreviewed

The Popa-Vaes paving conjecture over arbitrary maximal abelian subalgebras: strong-operator, approximation and quadratic paving

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Quadratic paper, Theorem 1.1: for 0<ε<10<\varepsilon<1 and rε≤5×108ε−2r_\varepsilon\le5\times10^8\varepsilon^{-2}, every self-adjoint xx in any von Neumann algebra MM is (ε,rε)(\varepsilon,r_\varepsilon) so-pavable over every MASA A⊆MA\subseteq M, with no separability or conditional expectation assumed; corollary: quadratic norm paving in Ocneanu ultrapowers of expected countably decomposable MASAs. Approximation paper, Theorem 1.…

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Quadratic paper, Theorem 1.1: for 0<ε<10<\varepsilon<1 and rε≤5×108ε−2r_\varepsilon\le5\times10^8\varepsilon^{-2}, every self-adjoint xx in any von Neumann algebra MM is (ε,rε)(\varepsilon,r_\varepsilon) so-pavable over every MASA A⊆MA\subseteq M, with no separability or conditional expectation assumed; corollary: quadratic norm paving in Ocneanu ultrapowers of expected countably decomposable MASAs. Approximation paper, Theorem 1.1: every self-adjoint xx is a strong limit of self-adjoint yy with ∥y∥≤3∥x∥\|y\|\le3\|x\|, each norm-pavable to error ε∥y∥\varepsilon\|y\| with at most Cε−6C\varepsilon^{-6} projections. Not shown: norm paving of the original operator (false in general), optimal numerical constants, or a quadratic rate for approximation paving.

Quadratic paper, Theorem 1.1: for 0<ε<10<\varepsilon<1 and rε≤5×108ε−2r_\varepsilon\le5\times10^8\varepsilon^{-2}, every self-adjoint xx in any von Neumann algebra MM is (ε,rε)(\varepsilon,r_\varepsilon) so-pavable over every MASA A⊆MA\subseteq M, with no separability or conditional expectation assumed; corollary: quadratic norm paving in Ocneanu ultrapowers of expected countably decomposable MASAs. Approximation paper, Theorem 1.1: every self-adjoint xx is a strong limit of self-adjoint yy with ∥y∥≤3∥x∥\|y\|\le3\|x\|, each norm-pavable to error ε∥y∥\varepsilon\|y\| with at most Cε−6C\varepsilon^{-6} projections. Not shown: norm paving of the original operator (false in general), optimal numerical constants, or a quadratic rate for approximation paving.

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