![]() |
Metamath Proof Explorer |
< Previous
Next >
Nearby theorems |
|
Mirrors > Home > MPE Home > Th. List > enfii | Structured version Visualization version GIF version |
Description: A set equinumerous to a finite set is finite. (Contributed by Mario Carneiro, 12-Mar-2015.) Avoid ax-pow 5370. (Revised by BTernaryTau, 23-Sep-2024.) |
Ref | Expression |
---|---|
enfii | ⊢ ((𝐵 ∈ Fin ∧ 𝐴 ≈ 𝐵) → 𝐴 ∈ Fin) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | isfi 9014 | . . . . . 6 ⊢ (𝐵 ∈ Fin ↔ ∃𝑥 ∈ ω 𝐵 ≈ 𝑥) | |
2 | df-rex 3068 | . . . . . 6 ⊢ (∃𝑥 ∈ ω 𝐵 ≈ 𝑥 ↔ ∃𝑥(𝑥 ∈ ω ∧ 𝐵 ≈ 𝑥)) | |
3 | 1, 2 | sylbb 219 | . . . . 5 ⊢ (𝐵 ∈ Fin → ∃𝑥(𝑥 ∈ ω ∧ 𝐵 ≈ 𝑥)) |
4 | ensymfib 9221 | . . . . . 6 ⊢ (𝐵 ∈ Fin → (𝐵 ≈ 𝐴 ↔ 𝐴 ≈ 𝐵)) | |
5 | 4 | biimparc 479 | . . . . 5 ⊢ ((𝐴 ≈ 𝐵 ∧ 𝐵 ∈ Fin) → 𝐵 ≈ 𝐴) |
6 | 19.41v 1946 | . . . . . 6 ⊢ (∃𝑥((𝑥 ∈ ω ∧ 𝐵 ≈ 𝑥) ∧ 𝐵 ≈ 𝐴) ↔ (∃𝑥(𝑥 ∈ ω ∧ 𝐵 ≈ 𝑥) ∧ 𝐵 ≈ 𝐴)) | |
7 | simp1 1135 | . . . . . . . . 9 ⊢ ((𝑥 ∈ ω ∧ 𝐵 ≈ 𝑥 ∧ 𝐵 ≈ 𝐴) → 𝑥 ∈ ω) | |
8 | nnfi 9205 | . . . . . . . . . 10 ⊢ (𝑥 ∈ ω → 𝑥 ∈ Fin) | |
9 | ensymfib 9221 | . . . . . . . . . . . . . 14 ⊢ (𝑥 ∈ Fin → (𝑥 ≈ 𝐵 ↔ 𝐵 ≈ 𝑥)) | |
10 | 9 | biimpar 477 | . . . . . . . . . . . . 13 ⊢ ((𝑥 ∈ Fin ∧ 𝐵 ≈ 𝑥) → 𝑥 ≈ 𝐵) |
11 | 10 | 3adant3 1131 | . . . . . . . . . . . 12 ⊢ ((𝑥 ∈ Fin ∧ 𝐵 ≈ 𝑥 ∧ 𝐵 ≈ 𝐴) → 𝑥 ≈ 𝐵) |
12 | entrfil 9222 | . . . . . . . . . . . 12 ⊢ ((𝑥 ∈ Fin ∧ 𝑥 ≈ 𝐵 ∧ 𝐵 ≈ 𝐴) → 𝑥 ≈ 𝐴) | |
13 | 11, 12 | syld3an2 1410 | . . . . . . . . . . 11 ⊢ ((𝑥 ∈ Fin ∧ 𝐵 ≈ 𝑥 ∧ 𝐵 ≈ 𝐴) → 𝑥 ≈ 𝐴) |
14 | ensymfib 9221 | . . . . . . . . . . . 12 ⊢ (𝑥 ∈ Fin → (𝑥 ≈ 𝐴 ↔ 𝐴 ≈ 𝑥)) | |
15 | 14 | 3ad2ant1 1132 | . . . . . . . . . . 11 ⊢ ((𝑥 ∈ Fin ∧ 𝐵 ≈ 𝑥 ∧ 𝐵 ≈ 𝐴) → (𝑥 ≈ 𝐴 ↔ 𝐴 ≈ 𝑥)) |
16 | 13, 15 | mpbid 232 | . . . . . . . . . 10 ⊢ ((𝑥 ∈ Fin ∧ 𝐵 ≈ 𝑥 ∧ 𝐵 ≈ 𝐴) → 𝐴 ≈ 𝑥) |
17 | 8, 16 | syl3an1 1162 | . . . . . . . . 9 ⊢ ((𝑥 ∈ ω ∧ 𝐵 ≈ 𝑥 ∧ 𝐵 ≈ 𝐴) → 𝐴 ≈ 𝑥) |
18 | 7, 17 | jca 511 | . . . . . . . 8 ⊢ ((𝑥 ∈ ω ∧ 𝐵 ≈ 𝑥 ∧ 𝐵 ≈ 𝐴) → (𝑥 ∈ ω ∧ 𝐴 ≈ 𝑥)) |
19 | 18 | 3expa 1117 | . . . . . . 7 ⊢ (((𝑥 ∈ ω ∧ 𝐵 ≈ 𝑥) ∧ 𝐵 ≈ 𝐴) → (𝑥 ∈ ω ∧ 𝐴 ≈ 𝑥)) |
20 | 19 | eximi 1831 | . . . . . 6 ⊢ (∃𝑥((𝑥 ∈ ω ∧ 𝐵 ≈ 𝑥) ∧ 𝐵 ≈ 𝐴) → ∃𝑥(𝑥 ∈ ω ∧ 𝐴 ≈ 𝑥)) |
21 | 6, 20 | sylbir 235 | . . . . 5 ⊢ ((∃𝑥(𝑥 ∈ ω ∧ 𝐵 ≈ 𝑥) ∧ 𝐵 ≈ 𝐴) → ∃𝑥(𝑥 ∈ ω ∧ 𝐴 ≈ 𝑥)) |
22 | 3, 5, 21 | syl2an2 686 | . . . 4 ⊢ ((𝐴 ≈ 𝐵 ∧ 𝐵 ∈ Fin) → ∃𝑥(𝑥 ∈ ω ∧ 𝐴 ≈ 𝑥)) |
23 | df-rex 3068 | . . . 4 ⊢ (∃𝑥 ∈ ω 𝐴 ≈ 𝑥 ↔ ∃𝑥(𝑥 ∈ ω ∧ 𝐴 ≈ 𝑥)) | |
24 | 22, 23 | sylibr 234 | . . 3 ⊢ ((𝐴 ≈ 𝐵 ∧ 𝐵 ∈ Fin) → ∃𝑥 ∈ ω 𝐴 ≈ 𝑥) |
25 | isfi 9014 | . . 3 ⊢ (𝐴 ∈ Fin ↔ ∃𝑥 ∈ ω 𝐴 ≈ 𝑥) | |
26 | 24, 25 | sylibr 234 | . 2 ⊢ ((𝐴 ≈ 𝐵 ∧ 𝐵 ∈ Fin) → 𝐴 ∈ Fin) |
27 | 26 | ancoms 458 | 1 ⊢ ((𝐵 ∈ Fin ∧ 𝐴 ≈ 𝐵) → 𝐴 ∈ Fin) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ↔ wb 206 ∧ wa 395 ∧ w3a 1086 ∃wex 1775 ∈ wcel 2105 ∃wrex 3067 class class class wbr 5147 ωcom 7886 ≈ cen 8980 Fincfn 8983 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1791 ax-4 1805 ax-5 1907 ax-6 1964 ax-7 2004 ax-8 2107 ax-9 2115 ax-10 2138 ax-11 2154 ax-12 2174 ax-ext 2705 ax-sep 5301 ax-nul 5311 ax-pr 5437 ax-un 7753 |
This theorem depends on definitions: df-bi 207 df-an 396 df-or 848 df-3or 1087 df-3an 1088 df-tru 1539 df-fal 1549 df-ex 1776 df-nf 1780 df-sb 2062 df-mo 2537 df-eu 2566 df-clab 2712 df-cleq 2726 df-clel 2813 df-nfc 2889 df-ne 2938 df-ral 3059 df-rex 3068 df-reu 3378 df-rab 3433 df-v 3479 df-sbc 3791 df-dif 3965 df-un 3967 df-in 3969 df-ss 3979 df-pss 3982 df-nul 4339 df-if 4531 df-pw 4606 df-sn 4631 df-pr 4633 df-op 4637 df-uni 4912 df-br 5148 df-opab 5210 df-tr 5265 df-id 5582 df-eprel 5588 df-po 5596 df-so 5597 df-fr 5640 df-we 5642 df-xp 5694 df-rel 5695 df-cnv 5696 df-co 5697 df-dm 5698 df-rn 5699 df-res 5700 df-ima 5701 df-ord 6388 df-on 6389 df-lim 6390 df-suc 6391 df-iota 6515 df-fun 6564 df-fn 6565 df-f 6566 df-f1 6567 df-fo 6568 df-f1o 6569 df-fv 6570 df-om 7887 df-1o 8504 df-en 8984 df-fin 8987 |
This theorem is referenced by: enfi 9224 domfi 9226 entrfi 9227 entrfir 9228 domsdomtrfi 9239 f1finf1o 9302 en1eqsnOLD 9306 isfinite2 9331 xpfiOLD 9356 fofinf1o 9369 cnvfiALT 9376 f1dmvrnfibi 9378 cantnfcl 9704 en2eqpr 10044 fzfi 14009 hasheni 14383 fz1isolem 14496 isercolllem2 15698 isercoll 15700 summolem2 15748 zsum 15750 prodmolem2 15967 zprod 15969 bitsf1 16479 simpgnsgd 20134 ovoliunlem1 25550 wlksnfi 29936 eupthfi 30233 eulerpartlemgs2 34361 derangenlem 35155 erdsze2lem2 35188 heicant 37641 sticksstones18 42145 sticksstones19 42146 |
Copyright terms: Public domain | W3C validator |