Definition:Upper Section

Definition
Let $\struct {S, \preceq}$ be an ordered set.

Let $U \subseteq S$.

Also known as
An upper set is also known as an upper-closed set or upward-closed set. Some sources call it an upset or up-set.

Also see

 * Equivalence of Definitions of Upper Section


 * Definition:Lower Section
 * Definition:Upper Closure