Math 2.0

statement theorem

Hausdorff maximal principle

Statement

Assume the axiom of choice. Let (P,≤)(P, \le) be a partially ordered set. Then each chain of PP is a subset of a maximal chain. A maximal chain is a chain that is not a proper subset of another chain of PP.

Remarks

Over ZF, the principle is equivalent to the axiom of choice and to Zorn's lemma. With the empty chain, it says that each partially ordered set has a maximal chain. Felix Hausdorff proved it in 1914.

Explanations

L1 human

Start with any chain in the order. You can extend it until no element can be added without breaking the chain property.

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Sources

  1. Web https://en.wikipedia.org/wiki/Hausdorff_maximal_principle, Statement