Every set can be well-ordered and you cannot convince me otherwise. AOC good.

    • hexaflexagonbear [he/him]
      ·
      4 years ago

      I hate the list of equivalent statements. Some are completely intuitive, others seem outlandish, but none seem like they should be related to eachother at all.

      • Puffin [any, they/them]
        hexagon
        ·
        4 years ago

        Honestly I'm pretty comfortable with most of the equivalent statements. Here are the statements I find especially intuitive:

        • The axiom of choice itself (the cartesian product of an infinite number of sets is non-empty)
        • Every surjective function has a right inverse
        • Trichotomy of set cardinality
        • Zorn's Lemma/Every vector space has a basis/Every ring has a maximal ideal/Every group has a maximal subgroup/Every connected graph has a spanning tree
        • Tychonoff's theorem
        • This one is equivalent to countable choice, but that a countable union of countable sets is countable
        • Well-ordering theorem

        Some of the weirder statements implied by it like Banach-Tarski/existence of non-Lebesgue measurable sets I just personally chalk up to general infinity weirdness in the same vein as something like Hilbert's Hotel.