The convex hull of two or more functions is the largest function that is concave from above and does not exceed the given functions.
Function Convex Hull
See also
Convex Hull, Shapiro's Cyclic Sum ConstantExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Function Convex Hull." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/FunctionConvexHull.html