Past exam of the mathematics course of the University of Cambridge 2021 iii Paper 158 1 iii Solution 2026-09-28
TakeThus is equivalent in ZF to . Indeed, this choice principle chooses one move from every nonempty value of a winning quasistrategy, turning it into a winning strategy in an infinite game. The converse encodes an arbitrary -indexed family of nonempty subsets of into a quasidetermined game. This is the choice characterization of quasideterminacy.