For every family {A_i}_{i∈I} of non-empty sets, there exists a choice function f with f(i) ∈ A_i for each i. Independent of ZF (Gödel 1938, Cohen 1963), equivalent to Zorn's lemma and the well-ordering theorem.
For every family {A_i}_{i∈I} of non-empty sets, there exists a choice function f with f(i) ∈ A_i for each i. Independent of ZF (Gödel 1938, Cohen 1963), equivalent to Zorn's lemma and the well-ordering theorem.