Ascending chain condition
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In mathematics, a poset P is said to satisfy the ascending chain condition (ACC) if every ascending chain a1 ≤ a2 ≤ ... of elements of P is eventually stationary, that is, there is some positive integer n such that am = an for all m > n. Similarly, P is said to satisfy the descending chain condition (DCC) if every descending chain a1 ≥ a2 ≥ ... of elements of P is eventually stationary (that is, there is no infinite descending chain).
The ascending chain condition on P is equivalent to the maximum condition: every nonempty subset of P has a maximal element. Similarly, the descending chain condition is equivalent to the minimum condition: every nonempty subset of P has a minimal element.
Every finite poset satisfies both ACC and DCC.
A totally ordered set that satisfies the descending chain condition is called a well-ordered set.
See also Noetherian and Artinian.zh:升链条件