Re: Inner Products



On Feb 16, 9:31 am, berwald.f...@xxxxxxxxxxxxxx wrote:
On 15 fev, 21:50, Mariano Suárez-Alvarez



<mariano.suarezalva...@xxxxxxxxx> wrote:
On 15 feb, 22:36, berwald.f...@xxxxxxxxxxxxxx wrote:

Hallo!

"Does the set of all inner products of a vector space have some
(algebraic, analytic, geometric) structure or interpretation?"
I saw this question in a blog... Any ideas?

By fixing a basis, you can identify a bilinear form
on a fginite dimensional space to a square matrix.
The form is non-degenerate iff the matrix has non-zero
determinant, and it is positive definite iff the determinants
of all its principal minors are positive.

This tells you that the set of inner products on a real
vector space is, in this identification, an open subset
of GL(n, R). It is this a real algebraic variety.

-- m

Thank you, Mariano.

I really liked this algebraic-geometric-topological thing!
Can you give me a reference for this, and/or some related questions?
By the way, what is the topology you are talking about?

The "usual" topology of GL(n, R) is the one it gets from
seeing it as a subset of M(n, R), the vector space of
n-by-n matrices.

-- m
.



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