.I want to show that (where is a vector space and is it's dual space) defined by:
What is here? An invertible operator (matrix), perhaps? Otherwise the redaction of the lemma/proposition/theorem is incomplete.
I have a proof from a book, but I don't quite understand what it's doing. It starts by:
Haven't they just proven it for just 0?
Also, what does "scalar product is definite" mean?