Minimal element

The notions of maximal and minimal elements are weaker than those of greatest element and least element which are also known, respectively, as maximum and minimum. The maximum of a subset ${\displaystyle S}$ of a preordered set is an element of ${\displaystyle S}$ which is greater than or equal to any other element of ${\displaystyle S,}$ and the minimum of ${\displaystyle S}$ is again defined dually. In the particular case of a partially ordered set, while there can be at most one maximum and at most one minimum there may be multiple maximal or minimal elements. Specializing further to totally ordered sets, the notions of maximal element and maximum coincide, and the notions of minimal element and minimum coincide.