Partial choice functions for families of finite sets

by Hall and Shelah. [HalSh:934]
Fundamenta Math, 2013
Let p be a prime. We show that ZF + ``Every countable set of p-element sets has an infinite partial choice function'' is not strong enough to prove that every countable set of p-element sets has a choice function, answering an open question from [1]. The independence result is obtained by way of a permutation (Fraenkel-Mostowski) model in which the set of atoms has the structure of a vector space over the field of p elements. By way of comparison, some simpler permutation models are considered in which some countable families of p-element sets fail to have infinite partial choice functions.

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