antichain

An antichain is a collection of elements in a partially ordered set (or poset) where no element is comparable to any other within the same set. In other words, for any two distinct elements in the antichain, neither is "less than" or "greater than" the other based on the given ordering. Imagine a set of tasks where none depends on or precedes another; these tasks form an antichain because they are all independent of each other. Antichains help identify groups of mutually incomparable elements within ordered systems.