span (A₁, . . . ,An) denotes the linear space spanned by Hilbert space operators A₁, . . . ,An. It is known that if span (A, B) consists of normal operators, then A, B commute. Let MI denote the set ...

L-moments are expectations of certain linear combinations of order statistics. They can be defined for any random variable whose mean exists and form the basis of a general theory which covers the ...