REPRESENTATION THEOREMS FOR INDEFINITE QUADRATIC FORMS REVISITED
REPRESENTATION THEOREMS FOR INDEFINITE QUADRATIC FORMS REVISITED
The first and second representation theorems for sign-indefinite, not necessarily semi-bounded quadratic forms are revisited. New and straightforward proofs of these theorems are given. A number of necessary and sufficient conditions for the second representation theorem to hold are obtained. A new simple and explicit example of a self-adjoint operator …