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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 7857 | . . . . 5 ⊢ (𝑥 ∈ ω → 𝑥 ∈ On) | |
2 | onfin 9229 | . . . . . 6 ⊢ (𝑥 ∈ On → (𝑥 ∈ Fin ↔ 𝑥 ∈ ω)) | |
3 | 2 | biimprcd 249 | . . . . 5 ⊢ (𝑥 ∈ ω → (𝑥 ∈ On → 𝑥 ∈ Fin)) |
4 | 1, 3 | jcai 516 | . . . 4 ⊢ (𝑥 ∈ ω → (𝑥 ∈ On ∧ 𝑥 ∈ Fin)) |
5 | 2 | biimpa 476 | . . . 4 ⊢ ((𝑥 ∈ On ∧ 𝑥 ∈ Fin) → 𝑥 ∈ ω) |
6 | 4, 5 | impbii 208 | . . 3 ⊢ (𝑥 ∈ ω ↔ (𝑥 ∈ On ∧ 𝑥 ∈ Fin)) |
7 | elin 3959 | . . 3 ⊢ (𝑥 ∈ (On ∩ Fin) ↔ (𝑥 ∈ On ∧ 𝑥 ∈ Fin)) | |
8 | 6, 7 | bitr4i 278 | . 2 ⊢ (𝑥 ∈ ω ↔ 𝑥 ∈ (On ∩ Fin)) |
9 | 8 | eqriv 2723 | 1 ⊢ ω = (On ∩ Fin) |
Colors of variables: wff setvar class |
Syntax hints: ∧ wa 395 = wceq 1533 ∈ wcel 2098 ∩ cin 3942 Oncon0 6357 ωcom 7851 Fincfn 8938 |
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-10 2129 ax-11 2146 ax-12 2163 ax-ext 2697 ax-sep 5292 ax-nul 5299 ax-pr 5420 ax-un 7721 |
This theorem depends on definitions: df-bi 206 df-an 396 df-or 845 df-3or 1085 df-3an 1086 df-tru 1536 df-fal 1546 df-ex 1774 df-nf 1778 df-sb 2060 df-mo 2528 df-eu 2557 df-clab 2704 df-cleq 2718 df-clel 2804 df-nfc 2879 df-ne 2935 df-ral 3056 df-rex 3065 df-reu 3371 df-rab 3427 df-v 3470 df-sbc 3773 df-csb 3889 df-dif 3946 df-un 3948 df-in 3950 df-ss 3960 df-pss 3962 df-nul 4318 df-if 4524 df-pw 4599 df-sn 4624 df-pr 4626 df-op 4630 df-uni 4903 df-br 5142 df-opab 5204 df-mpt 5225 df-tr 5259 df-id 5567 df-eprel 5573 df-po 5581 df-so 5582 df-fr 5624 df-we 5626 df-xp 5675 df-rel 5676 df-cnv 5677 df-co 5678 df-dm 5679 df-rn 5680 df-res 5681 df-ima 5682 df-ord 6360 df-on 6361 df-lim 6362 df-suc 6363 df-iota 6488 df-fun 6538 df-fn 6539 df-f 6540 df-f1 6541 df-fo 6542 df-f1o 6543 df-fv 6544 df-om 7852 df-1o 8464 df-en 8939 df-dom 8940 df-sdom 8941 df-fin 8942 |
This theorem is referenced by: nnfiOLD 9231 cantnfcl 9661 ackbij1lem9 10222 ackbij1lem10 10223 ackbij1b 10233 sdom2en01 10296 fin23lem26 10319 fin56 10387 fin1a2lem9 10402 fzfi 13940 fz1isolem 14426 ackbijnn 15778 hauspwdom 23356 0finon 42756 1finon 42757 2finon 42758 3finon 42759 4finon 42760 finona1cl 42761 finonex 42762 dfom6 42839 |
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