The
ascending chain condition (ACC) and
descending chain condition (DCC) are finiteness properties satisfied by certain algebraic structures, most importantly,
ideals in a
commutative ring. These conditions played an important role in the development of the structure theory of commutative rings in the works of
David Hilbert,
Emmy Noether, and
Emil Artin.
The conditions themselves can be stated in an abstract form, so that they make sense for any
partially ordered set. This point of view is useful in abstract algebraic dimension theory due to Gabriel and Rentschler.
Definition
A
partially ordered set (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).
Comments
- The descending chain condition on P is equivalent to P being well-founded: every nonempty subset of P has a minimal element (also called the minimal condition).
- Similarly, the ascending chain condition is equivalent to P being converse well-founded: every nonempty subset of P has a maximal element (the maximal condition).
- 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
References