Characterization of operators which are scalar multiple of the identity
4280
A linear operator commuting with all such operators is a scalar multiple of the identity.
119352
compact and self adjoint square root of an operator
87897
Bounded operators on separable Hilbert spaces
78592
Tensor product of Hadamard operators
54628
Properties of non-zero symmetric bilinear form
99942
A normal, idempotent linear operator must be self-adjoint
54668
Proof for the completeness of eigenfunctions of a self-adjoint operator
85019
How are big operators defined?
144019
A strictly positive operator is invertible
112900
Eigenvalue of a polynomial evaluated in a operator
138784
Is the differentiation operator an open mapping?
29470
Problem involving Derivative and Antiderivative operators in Hoffman and Kunze's Linear Algebra
88535
Relation between the distance from a point to the resolvent set of a self-adjoint operator and the norm of a related operator
71316
Two inner products being equal up to a scalar
127882
Proofs involving orthonormal basis
122305
Proof of matrix norm property: submultiplicativity
44371
Finding trace and determinant of linear operator