A minimum of a subset
A⊆R is an element m∈A such that m≤x for every x∈A.
If a minimum exists, it is unique and equals the infimum
of A. Many sets have an infimum but no minimum (for instance, open intervals).
Examples:
- For A=[0,1], the minimum is 0.
- For A={2,5,3}, the minimum is 2.