The PFA(S)[S] conjecture on first-countable perfect pre-images of ω1\omega_1ω1
PFA(S)[S] conjecture. Under PFA(S)[S]\mathrm{PFA}(S)[S]PFA(S)[S], every first-countable perfect pre-image of ω1\omega_1ω1 includes a copy of ω1\omega_1ω1.