convex set

check the definition in real analysis here convex set

Set 𝑆𝑛 is a convex set if it contains a line segment between any two of it’s points.

convex function

Function 𝑓:𝑆𝑛 is convex function on convex set 𝑆 if it’s graph along any line segment in 𝑆 lies on or below chord connecting function values at endpoints of segment.

Def

Any local minimum of convex function 𝑓 on convex set 𝑆 is global minimum of 𝑓 on 𝑆.

Def

Any local minimum of strictly convex function 𝑓 on convex set 𝑆 is unique global minimum of 𝑓 on 𝑆.