A global extremum, also known as an absolute extremum, is a global minimum or global maximum. It is impossible to construct an algorithm that will find a global extremum for an arbitrary function.
Global Extremum
See also
Local ExtremumExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Global Extremum." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/GlobalExtremum.html