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Mirrors > Home > MPE Home > Th. List > onfin2 | Structured version Visualization version GIF version |
Description: A set is a natural number iff it is a finite ordinal. (Contributed by Mario Carneiro, 22-Jan-2013.) |
Ref | Expression |
---|---|
onfin2 | ⊢ ω = (On ∩ Fin) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | nnon 7566 | . . . . 5 ⊢ (𝑥 ∈ ω → 𝑥 ∈ On) | |
2 | onfin 8694 | . . . . . 6 ⊢ (𝑥 ∈ On → (𝑥 ∈ Fin ↔ 𝑥 ∈ ω)) | |
3 | 2 | biimprcd 253 | . . . . 5 ⊢ (𝑥 ∈ ω → (𝑥 ∈ On → 𝑥 ∈ Fin)) |
4 | 1, 3 | jcai 520 | . . . 4 ⊢ (𝑥 ∈ ω → (𝑥 ∈ On ∧ 𝑥 ∈ Fin)) |
5 | 2 | biimpa 480 | . . . 4 ⊢ ((𝑥 ∈ On ∧ 𝑥 ∈ Fin) → 𝑥 ∈ ω) |
6 | 4, 5 | impbii 212 | . . 3 ⊢ (𝑥 ∈ ω ↔ (𝑥 ∈ On ∧ 𝑥 ∈ Fin)) |
7 | elin 3897 | . . 3 ⊢ (𝑥 ∈ (On ∩ Fin) ↔ (𝑥 ∈ On ∧ 𝑥 ∈ Fin)) | |
8 | 6, 7 | bitr4i 281 | . 2 ⊢ (𝑥 ∈ ω ↔ 𝑥 ∈ (On ∩ Fin)) |
9 | 8 | eqriv 2795 | 1 ⊢ ω = (On ∩ Fin) |
Colors of variables: wff setvar class |
Syntax hints: ∧ wa 399 = wceq 1538 ∈ wcel 2111 ∩ cin 3880 Oncon0 6159 ωcom 7560 Fincfn 8492 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1797 ax-4 1811 ax-5 1911 ax-6 1970 ax-7 2015 ax-8 2113 ax-9 2121 ax-10 2142 ax-11 2158 ax-12 2175 ax-ext 2770 ax-sep 5167 ax-nul 5174 ax-pow 5231 ax-pr 5295 ax-un 7441 |
This theorem depends on definitions: df-bi 210 df-an 400 df-or 845 df-3or 1085 df-3an 1086 df-tru 1541 df-ex 1782 df-nf 1786 df-sb 2070 df-mo 2598 df-eu 2629 df-clab 2777 df-cleq 2791 df-clel 2870 df-nfc 2938 df-ne 2988 df-ral 3111 df-rex 3112 df-rab 3115 df-v 3443 df-sbc 3721 df-dif 3884 df-un 3886 df-in 3888 df-ss 3898 df-pss 3900 df-nul 4244 df-if 4426 df-pw 4499 df-sn 4526 df-pr 4528 df-tp 4530 df-op 4532 df-uni 4801 df-br 5031 df-opab 5093 df-tr 5137 df-id 5425 df-eprel 5430 df-po 5438 df-so 5439 df-fr 5478 df-we 5480 df-xp 5525 df-rel 5526 df-cnv 5527 df-co 5528 df-dm 5529 df-rn 5530 df-res 5531 df-ima 5532 df-ord 6162 df-on 6163 df-lim 6164 df-suc 6165 df-iota 6283 df-fun 6326 df-fn 6327 df-f 6328 df-f1 6329 df-fo 6330 df-f1o 6331 df-fv 6332 df-om 7561 df-er 8272 df-en 8493 df-dom 8494 df-sdom 8495 df-fin 8496 |
This theorem is referenced by: nnfi 8696 cantnfcl 9114 ackbij1lem9 9639 ackbij1lem10 9640 ackbij1b 9650 sdom2en01 9713 fin23lem26 9736 fin56 9804 fin1a2lem9 9819 fzfi 13335 fz1isolem 13815 ackbijnn 15175 hauspwdom 22106 dfom6 40239 |
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