As an example, in the set of integers, the chain −1, −2, −3, ... is an infinite descending chain, but there exists no infinite descending chain on the natural numbers, as every chain of natural numbers has a minimal element.
作为例子，在整数的集合中，链−1, −2, −3, ...是无穷降链，但是在自然数上没有无穷降链，所有自然数的链都有一个极小元素。