In this note we give some two by two block matrices M = (A X X* B) where M and M' = (A X* X B) are unitarily congruent. We also generalize a class of positive semi-definite block-matrices satisfying the inequality parallel to M parallel to <= parallel to A+ B parallel to for all symmetric norms.
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机译：在本说明中，我们通过两个块矩阵M =（a x x * b）给出两个，其中m和m'=（x * x b）一致地是一致的。 我们还概括了一类充满平行于<=平行于与所有对称规范的+ B平行的不等式的正半定块矩阵。
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