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Mirrors > Home > MPE Home > Th. List > isfinite4 | Structured version Visualization version GIF version |
Description: A finite set is equinumerous to the range of integers from one up to the hash value of the set. In other words, counting objects with natural numbers works if and only if it is a finite collection. (Contributed by Richard Penner, 26-Feb-2020.) |
Ref | Expression |
---|---|
isfinite4 | ⊢ (𝐴 ∈ Fin ↔ (1...(♯‘𝐴)) ≈ 𝐴) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | hashcl 13713 | . . . 4 ⊢ (𝐴 ∈ Fin → (♯‘𝐴) ∈ ℕ0) | |
2 | hashfz1 13702 | . . . 4 ⊢ ((♯‘𝐴) ∈ ℕ0 → (♯‘(1...(♯‘𝐴))) = (♯‘𝐴)) | |
3 | 1, 2 | syl 17 | . . 3 ⊢ (𝐴 ∈ Fin → (♯‘(1...(♯‘𝐴))) = (♯‘𝐴)) |
4 | fzfi 13335 | . . . 4 ⊢ (1...(♯‘𝐴)) ∈ Fin | |
5 | hashen 13703 | . . . 4 ⊢ (((1...(♯‘𝐴)) ∈ Fin ∧ 𝐴 ∈ Fin) → ((♯‘(1...(♯‘𝐴))) = (♯‘𝐴) ↔ (1...(♯‘𝐴)) ≈ 𝐴)) | |
6 | 4, 5 | mpan 689 | . . 3 ⊢ (𝐴 ∈ Fin → ((♯‘(1...(♯‘𝐴))) = (♯‘𝐴) ↔ (1...(♯‘𝐴)) ≈ 𝐴)) |
7 | 3, 6 | mpbid 235 | . 2 ⊢ (𝐴 ∈ Fin → (1...(♯‘𝐴)) ≈ 𝐴) |
8 | ensym 8541 | . . 3 ⊢ ((1...(♯‘𝐴)) ≈ 𝐴 → 𝐴 ≈ (1...(♯‘𝐴))) | |
9 | enfi 8718 | . . . 4 ⊢ (𝐴 ≈ (1...(♯‘𝐴)) → (𝐴 ∈ Fin ↔ (1...(♯‘𝐴)) ∈ Fin)) | |
10 | 9 | biimprcd 253 | . . 3 ⊢ ((1...(♯‘𝐴)) ∈ Fin → (𝐴 ≈ (1...(♯‘𝐴)) → 𝐴 ∈ Fin)) |
11 | 4, 8, 10 | mpsyl 68 | . 2 ⊢ ((1...(♯‘𝐴)) ≈ 𝐴 → 𝐴 ∈ Fin) |
12 | 7, 11 | impbii 212 | 1 ⊢ (𝐴 ∈ Fin ↔ (1...(♯‘𝐴)) ≈ 𝐴) |
Colors of variables: wff setvar class |
Syntax hints: ↔ wb 209 = wceq 1538 ∈ wcel 2111 class class class wbr 5030 ‘cfv 6324 (class class class)co 7135 ≈ cen 8489 Fincfn 8492 1c1 10527 ℕ0cn0 11885 ...cfz 12885 ♯chash 13686 |
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 ax-cnex 10582 ax-resscn 10583 ax-1cn 10584 ax-icn 10585 ax-addcl 10586 ax-addrcl 10587 ax-mulcl 10588 ax-mulrcl 10589 ax-mulcom 10590 ax-addass 10591 ax-mulass 10592 ax-distr 10593 ax-i2m1 10594 ax-1ne0 10595 ax-1rid 10596 ax-rnegex 10597 ax-rrecex 10598 ax-cnre 10599 ax-pre-lttri 10600 ax-pre-lttrn 10601 ax-pre-ltadd 10602 ax-pre-mulgt0 10603 |
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-nel 3092 df-ral 3111 df-rex 3112 df-reu 3113 df-rab 3115 df-v 3443 df-sbc 3721 df-csb 3829 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-int 4839 df-iun 4883 df-br 5031 df-opab 5093 df-mpt 5111 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-pred 6116 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-riota 7093 df-ov 7138 df-oprab 7139 df-mpo 7140 df-om 7561 df-1st 7671 df-2nd 7672 df-wrecs 7930 df-recs 7991 df-rdg 8029 df-1o 8085 df-er 8272 df-en 8493 df-dom 8494 df-sdom 8495 df-fin 8496 df-card 9352 df-pnf 10666 df-mnf 10667 df-xr 10668 df-ltxr 10669 df-le 10670 df-sub 10861 df-neg 10862 df-nn 11626 df-n0 11886 df-z 11970 df-uz 12232 df-fz 12886 df-hash 13687 |
This theorem is referenced by: fz1f1o 15059 padct 30481 rp-isfinite5 40225 |
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