Cycles and 1-unconditional matrices
نویسنده
چکیده
We characterize the 1-unconditional subsets (erc)(r,c)∈I of the set of elementary matrices in the Schatten-von-Neumann class S. The set of couples I must be the set of edges of a bipartite graph without cycles of even length 4 6 l 6 p if p is an even integer, and without cycles at all if p is a positive real number that is not an even integer. In the latter case, I is even a Varopoulos set of V -interpolation of constant 1. We also study the metric unconditional approximation property for the space S I spanned by (erc)(r,c)∈I in S .
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