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math.CA2026
A characterization of idempotent Schur multipliers
Csongor Beke, Marcel K. Goh, Hamed Hatami +2
We prove that every idempotent Schur multiplier is a finite signed sum of contractive idempotent Schur multipliers. This was conjectured by Katavolos and Paulsen in 2003 and previo…
math.CA2025
Block structure in boolean matrices of bounded factorization norm
Marcel K. Goh, Hamed Hatami
A boolean matrix is blocky if its -entries form a collection of 1-monochromatic submatrices that are disjoint in both rows and columns. Blocky matrices are precisely the set of…
math.CA2025
Block complexity and idempotent Schur multipliers
Marcel K. Goh, Hamed Hatami
We call a matrix blocky if, up to row and column permutations, it can be obtained from an identity matrix by repeatedly applying one of the following operations: duplicating a row,…