Theorem ssct 9088

Description: Any subset of a countable set is countable. (Contributed by Thierry Arnoux, 31-Jan-2017.) Avoid ax-pow 5368, ax-un 7745. (Revised by BTernaryTau, 7-Dec-2024.)

Assertion

Ref	Expression
ssct	⊢ ((𝐴 ⊆ 𝐵 ∧ 𝐵 ≼ ω) → 𝐴 ≼ ω)

Proof of Theorem ssct

Step	Hyp	Ref	Expression
1		domssl 9028	1 ⊢ ((𝐴 ⊆ 𝐵 ∧ 𝐵 ≼ ω) → 𝐴 ≼ ω)

Syntax hints:   → wi 4   ∧ wa 394   ⊆ wss 3946   class class class wbr 5152  ωcom 7875   ≼ cdom 8971

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1789  ax-4 1803  ax-5 1905  ax-6 1963  ax-7 2003  ax-8 2100  ax-9 2108  ax-ext 2696  ax-sep 5303  ax-nul 5310  ax-pr 5432

This theorem depends on definitions:  df-bi 206  df-an 395  df-or 846  df-3an 1086  df-tru 1536  df-fal 1546  df-ex 1774  df-sb 2060  df-clab 2703  df-cleq 2717  df-clel 2802  df-ral 3051  df-rex 3060  df-rab 3419  df-v 3463  df-dif 3949  df-un 3951  df-in 3953  df-ss 3963  df-nul 4325  df-if 4533  df-sn 4633  df-pr 4635  df-op 4639  df-br 5153  df-opab 5215  df-xp 5687  df-rel 5688  df-cnv 5689  df-co 5690  df-dm 5691  df-rn 5692  df-res 5693  df-fun 6555  df-fn 6556  df-f 6557  df-f1 6558  df-dom 8975

This theorem is referenced by:  measvuni  34003  measiuns  34006  sxbrsigalem1  34075  ssnct  44615  fzct  44931  fzoct  44936  salexct  45892  opnvonmbllem2  46191