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Mirrors > Home > MPE Home > Th. List > Mathboxes > ctbnfien | Structured version Visualization version GIF version |
Description: An infinite subset of a countable set is countable, without using choice. (Contributed by Stefan O'Rear, 19-Oct-2014.) (Revised by Stefan O'Rear, 6-May-2015.) |
Ref | Expression |
---|---|
ctbnfien | ⊢ (((𝑋 ≈ ω ∧ 𝑌 ≈ ω) ∧ (𝐴 ⊆ 𝑋 ∧ ¬ 𝐴 ∈ Fin)) → 𝐴 ≈ 𝑌) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | isfinite 9191 | . . . . 5 ⊢ (𝐴 ∈ Fin ↔ 𝐴 ≺ ω) | |
2 | 1 | notbii 323 | . . . 4 ⊢ (¬ 𝐴 ∈ Fin ↔ ¬ 𝐴 ≺ ω) |
3 | relen 8563 | . . . . . . . . . . 11 ⊢ Rel ≈ | |
4 | 3 | brrelex1i 5580 | . . . . . . . . . 10 ⊢ (𝑋 ≈ ω → 𝑋 ∈ V) |
5 | ssdomg 8604 | . . . . . . . . . 10 ⊢ (𝑋 ∈ V → (𝐴 ⊆ 𝑋 → 𝐴 ≼ 𝑋)) | |
6 | 4, 5 | syl 17 | . . . . . . . . 9 ⊢ (𝑋 ≈ ω → (𝐴 ⊆ 𝑋 → 𝐴 ≼ 𝑋)) |
7 | domen2 8713 | . . . . . . . . 9 ⊢ (𝑋 ≈ ω → (𝐴 ≼ 𝑋 ↔ 𝐴 ≼ ω)) | |
8 | 6, 7 | sylibd 242 | . . . . . . . 8 ⊢ (𝑋 ≈ ω → (𝐴 ⊆ 𝑋 → 𝐴 ≼ ω)) |
9 | 8 | imp 410 | . . . . . . 7 ⊢ ((𝑋 ≈ ω ∧ 𝐴 ⊆ 𝑋) → 𝐴 ≼ ω) |
10 | brdom2 8588 | . . . . . . 7 ⊢ (𝐴 ≼ ω ↔ (𝐴 ≺ ω ∨ 𝐴 ≈ ω)) | |
11 | 9, 10 | sylib 221 | . . . . . 6 ⊢ ((𝑋 ≈ ω ∧ 𝐴 ⊆ 𝑋) → (𝐴 ≺ ω ∨ 𝐴 ≈ ω)) |
12 | 11 | adantlr 715 | . . . . 5 ⊢ (((𝑋 ≈ ω ∧ 𝑌 ≈ ω) ∧ 𝐴 ⊆ 𝑋) → (𝐴 ≺ ω ∨ 𝐴 ≈ ω)) |
13 | 12 | ord 863 | . . . 4 ⊢ (((𝑋 ≈ ω ∧ 𝑌 ≈ ω) ∧ 𝐴 ⊆ 𝑋) → (¬ 𝐴 ≺ ω → 𝐴 ≈ ω)) |
14 | 2, 13 | syl5bi 245 | . . 3 ⊢ (((𝑋 ≈ ω ∧ 𝑌 ≈ ω) ∧ 𝐴 ⊆ 𝑋) → (¬ 𝐴 ∈ Fin → 𝐴 ≈ ω)) |
15 | 14 | impr 458 | . 2 ⊢ (((𝑋 ≈ ω ∧ 𝑌 ≈ ω) ∧ (𝐴 ⊆ 𝑋 ∧ ¬ 𝐴 ∈ Fin)) → 𝐴 ≈ ω) |
16 | enen2 8711 | . . 3 ⊢ (𝑌 ≈ ω → (𝐴 ≈ 𝑌 ↔ 𝐴 ≈ ω)) | |
17 | 16 | ad2antlr 727 | . 2 ⊢ (((𝑋 ≈ ω ∧ 𝑌 ≈ ω) ∧ (𝐴 ⊆ 𝑋 ∧ ¬ 𝐴 ∈ Fin)) → (𝐴 ≈ 𝑌 ↔ 𝐴 ≈ ω)) |
18 | 15, 17 | mpbird 260 | 1 ⊢ (((𝑋 ≈ ω ∧ 𝑌 ≈ ω) ∧ (𝐴 ⊆ 𝑋 ∧ ¬ 𝐴 ∈ Fin)) → 𝐴 ≈ 𝑌) |
Colors of variables: wff setvar class |
Syntax hints: ¬ wn 3 → wi 4 ↔ wb 209 ∧ wa 399 ∨ wo 846 ∈ wcel 2114 Vcvv 3399 ⊆ wss 3844 class class class wbr 5031 ωcom 7602 ≈ cen 8555 ≼ cdom 8556 ≺ csdm 8557 Fincfn 8558 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1802 ax-4 1816 ax-5 1917 ax-6 1975 ax-7 2020 ax-8 2116 ax-9 2124 ax-10 2145 ax-11 2162 ax-12 2179 ax-ext 2711 ax-sep 5168 ax-nul 5175 ax-pow 5233 ax-pr 5297 ax-un 7482 ax-inf2 9180 |
This theorem depends on definitions: df-bi 210 df-an 400 df-or 847 df-3or 1089 df-3an 1090 df-tru 1545 df-fal 1555 df-ex 1787 df-nf 1791 df-sb 2075 df-mo 2541 df-eu 2571 df-clab 2718 df-cleq 2731 df-clel 2812 df-nfc 2882 df-ne 2936 df-ral 3059 df-rex 3060 df-reu 3061 df-rab 3063 df-v 3401 df-sbc 3682 df-csb 3792 df-dif 3847 df-un 3849 df-in 3851 df-ss 3861 df-pss 3863 df-nul 4213 df-if 4416 df-pw 4491 df-sn 4518 df-pr 4520 df-tp 4522 df-op 4524 df-uni 4798 df-int 4838 df-iun 4884 df-br 5032 df-opab 5094 df-mpt 5112 df-tr 5138 df-id 5430 df-eprel 5435 df-po 5443 df-so 5444 df-fr 5484 df-we 5486 df-xp 5532 df-rel 5533 df-cnv 5534 df-co 5535 df-dm 5536 df-rn 5537 df-res 5538 df-ima 5539 df-pred 6130 df-ord 6176 df-on 6177 df-lim 6178 df-suc 6179 df-iota 6298 df-fun 6342 df-fn 6343 df-f 6344 df-f1 6345 df-fo 6346 df-f1o 6347 df-fv 6348 df-om 7603 df-wrecs 7979 df-recs 8040 df-rdg 8078 df-1o 8134 df-er 8323 df-en 8559 df-dom 8560 df-sdom 8561 df-fin 8562 |
This theorem is referenced by: fiphp3d 40236 irrapx1 40245 |
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