Order preservation by the positive square root

ID: order-preservation-by-the-positive-square-root

For Positive elements of a C-star algebra , inversion reverses the order of strictly positive elements, so for . Subtracting their square-root resolvent integral in a C-star algebra formulas gives
The integrand is positive, and the positive cone is closed, so the norm limit of these integrals is positive. No commutativity of and is required. In particular, for positive implies , even though squaring itself is not generally order preserving.

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