Definition:Discriminant of Bilinear Form

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Definition

Let $\mathbb K$ be a field.

Let $V$ be a vector space over $\mathbb K$ of finite dimension $n>0$.

Let $b : V\times V \to \mathbb K$ be a bilinear form on $V$.

Let $A$ be the matrix of $b$ relative to an ordered basis of $V$.


If $b$ is nondegenerate, its discriminant is the equivalence class of the determinant $\det A$ in the quotient group $\dfrac {\mathbb K^\times} {\paren {\mathbb K^\times}^2}$.

If $b$ is degenerate, its discriminant is $0$.


Also defined as

Some authors simply do not define the discriminant of a degenerate bilinear form.


Also see


Sources