Principle of covariance

A bilinear form, a(•,•) whose arguments are elements of normed vector space V is a strongly positive bilinear form if and only if there exists a constant, c>0, such that

$a(u,u)\ge c\cdot \Vert u{\Vert }^2$

for all $u\in V$ where $\Vert \cdot \Vert$ is the norm on V.

References

• AMS 108 p.120