⊢ ω₁ = sup {a | countableOrd a}
⊢ ¬countable 𝕌(:α ucinf)
⊢ 𝕌(:num) <= 𝕌(:α ucinf)
⊢ 𝕌(:num) ≼ 𝕌(:α ucinf)
⊢ {a | countableOrd a} ≼ 𝕌(:α ucinf)
⊢ x < ω₁ ⇔ countableOrd x
⊢ ¬countableOrd ω₁