partially ordered set

A partially ordered set, or poset, is a collection of elements where some pairs can be compared to see which comes before or after, but not necessarily all pairs. For example, in a set of tasks, some tasks must be done before others, but some can be done in any order. The "partial order" means there’s a relation that’s reflexive (every element relates to itself), antisymmetric (if one element relates to another and vice versa, then they are the same), and transitive (if one relates to a second, and that second relates to a third, then the first relates to the third).