A set-indexed family of sets is said to be a collection family if for any and any surjection , there exists a and a surjection which factors through .
The axiom of multiple choice states one of two things:
The second formulation seems to be the one originally given by M&P, below, while the first is that given by Rathjen and attributed to Aczel and Simpson.
Mike Shulman: Are these the same? If not, why are they given the same name?
Note that is a projective set if and only if the singleton family is a collection family. Therefore, since AC is equivalent to “all sets are projective,” it implies AMC.
An extension of this argument shows that COSHEP is sufficient to imply AMC.
The Reflection Principle? (RP) is equivalent to AMC (called stong AMC by van den Berg). RP is motivated by the regular extension principle (REA) from constructive set theory. RP states that every map belongs to a representable class of small maps.
However, AMC does not imply countable choice or any of the other usual consequences of AC.
Rathjen proves that SVC also implies AMC. It follows that AMC holds in “most” models of set theory.
Rathjen, “Choice principles in constructive and classical set theories”
WISC is called the “axiom of multiple choice”.