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 ) ≥ c ⋅ ‖ u ‖ 2 {\displaystyle a(u,u)\geq c\cdot \|u\|^{2}}
for all u ∈ V {\displaystyle u\in V} where ‖ ⋅ ‖ {\displaystyle \|\cdot \|} is the norm on V.
References AMS 108 p.120