Consequences of W_{ℵ1}: PS1 and P-space existence for 2^Y[[Y]^{≤ω}]
Determine whether the comparability principle W_{ℵ1} implies either of the following in ZF: (a) for every uncountable set X there exists an uncountable Y⊆X such that 2^{Y}[[Y]^{≤ω}] is a P-space; or (b) PS1 (that for every uncountable set X there exists an uncountable Y⊆X such that S(Y,[Y]^{≤ω}) is a P-space).
References
We do not know whether or not $\mathbf{W}{\aleph{1}}$ implies either of “For every uncountable set $X$, there exists an uncountable set $Y\subseteq X$ such that $2{Y}[[Y]{\leq\omega}]$ is a $P$-space” or $\mathbf{PS}_1$ in $\mathbf{ZF}$.
— Constructing crowded Hausdorff $P$-spaces in set theory without the axiom of choice
(2510.11935 - Tachtsis et al., 13 Oct 2025) in Section 9, Remark rem:W_aleph