Team games, hypergraph spaces, and projective Boolean algebras
Abstract
We modify the game Fuchino, Koppelberg, and Shelah used to characterize the -Freese-Nation property for a given Boolean algebra , replacing players I and II each with a team of players with limited information. We show that is tightly -filtered exactly when team II has a winning strategy for every finite team size. Case characterizes projective Boolean algebras and, hence, Dugundji spaces. In terms of the open-open game of Daniels, Kunen, and Zhou, this characterization is a team version of very I-favorable. We similarly characterize Cohen algebras in terms of a team version of I-favorability. If is the clopen algebra of the space of -uniform hypergraphs on that avoid copies of , then team II has a winning strategy for our modified FKS game for team size but not . For , this algebra also answers a question of Geschke when combined with a locally -sized characterization of tightly -filtered Boolean algebras that we prove. Case includes a locally finite characterization of projective Boolean algebras.
Keywords
Cite
@article{arxiv.1607.07944,
title = {Team games, hypergraph spaces, and projective Boolean algebras},
author = {David Milovich},
journal= {arXiv preprint arXiv:1607.07944},
year = {2022}
}
Comments
Greatly simplified main construction and extended results to Cohen and $\kappa$-tightly filtered algebras