Cauchy-Schwarz inequality

Cauchy-Schwarz inequality
The Cauchy-Schwarz inequality places an upper bound on the absolute value of the expectation of the product of two r.v. : ...

See also Cauchy-Schwarz inequality.
Reversal in Minkowski space
In the usual Minkowski space and in Minkowski space extended to an arbitrary number of spatial dimensions, assuming null or timelike vectors in the same time direction, ...