Problems / analysis
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<1 and rε≤5×108ε−2, every self-adjoint x in any von Neumann algebra M is (ε,rε) so-pavable over every MASA A⊆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 x is a strong limit of self-adjoint y with ∥y∥≤3∥x∥, each norm-pavable to error ε∥y∥ with at most Cε−6 projections. Not shown: norm paving of the original operator (false in general), optimal numerical constants, or a quadratic rate for approximation paving.