A maximum of a ARA\subseteq\mathbb R is an element mAm\in A such that xmx\le m for every xAx\in A.

Remarks

If a maximum exists, it is unique and equals the of AA. Many sets have a supremum but no maximum (for instance, open intervals).

Examples
  • For A=[0,1]A=[0,1], the maximum is 11.
  • For A={2,5,3}A=\{2,5,3\}, the maximum is 55.