almost unitary subset

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• Unitary group — In mathematics, the unitary group of degree n , denoted U( n ), is the group of n times; n unitary matrices, with the group operation that of matrix multiplication. The unitary group is a subgroup of the general linear group GL( n , C).In the… …   Wikipedia

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• Direct integral — In mathematics and functional analysis a direct integral is a generalization of the concept of direct sum. The theory is most developed for direct integrals of Hilbert spaces and direct integrals of von Neumann algebras. The concept was… …   Wikipedia

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