A differentiable function f on a convex, open set S in n is convex if and only if for every x0; x S. f is

A differentiable function f on a convex, open set S in „œn is convex if and only if

for every x0; x ˆˆ S. f is strictly convex if and only if

for every x ‰  x0 ˆˆ S.

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