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Mirrors > Home > MPE Home > Th. List > hashen1 | Structured version Visualization version GIF version |
Description: A set has size 1 if and only if it is equinumerous to the ordinal 1. (Contributed by AV, 14-Apr-2019.) |
Ref | Expression |
---|---|
hashen1 | ⊢ (𝐴 ∈ 𝑉 → ((♯‘𝐴) = 1 ↔ 𝐴 ≈ 1o)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | 0ex 5313 | . . . . . 6 ⊢ ∅ ∈ V | |
2 | hashsng 14405 | . . . . . 6 ⊢ (∅ ∈ V → (♯‘{∅}) = 1) | |
3 | 1, 2 | ax-mp 5 | . . . . 5 ⊢ (♯‘{∅}) = 1 |
4 | 3 | eqcomi 2744 | . . . 4 ⊢ 1 = (♯‘{∅}) |
5 | 4 | a1i 11 | . . 3 ⊢ (𝐴 ∈ 𝑉 → 1 = (♯‘{∅})) |
6 | 5 | eqeq2d 2746 | . 2 ⊢ (𝐴 ∈ 𝑉 → ((♯‘𝐴) = 1 ↔ (♯‘𝐴) = (♯‘{∅}))) |
7 | simpr 484 | . . . . 5 ⊢ ((𝐴 ∈ 𝑉 ∧ (♯‘𝐴) = (♯‘{∅})) → (♯‘𝐴) = (♯‘{∅})) | |
8 | 1nn0 12540 | . . . . . . . . 9 ⊢ 1 ∈ ℕ0 | |
9 | 3, 8 | eqeltri 2835 | . . . . . . . 8 ⊢ (♯‘{∅}) ∈ ℕ0 |
10 | hashvnfin 14396 | . . . . . . . 8 ⊢ ((𝐴 ∈ 𝑉 ∧ (♯‘{∅}) ∈ ℕ0) → ((♯‘𝐴) = (♯‘{∅}) → 𝐴 ∈ Fin)) | |
11 | 9, 10 | mpan2 691 | . . . . . . 7 ⊢ (𝐴 ∈ 𝑉 → ((♯‘𝐴) = (♯‘{∅}) → 𝐴 ∈ Fin)) |
12 | 11 | imp 406 | . . . . . 6 ⊢ ((𝐴 ∈ 𝑉 ∧ (♯‘𝐴) = (♯‘{∅})) → 𝐴 ∈ Fin) |
13 | snfi 9082 | . . . . . 6 ⊢ {∅} ∈ Fin | |
14 | hashen 14383 | . . . . . 6 ⊢ ((𝐴 ∈ Fin ∧ {∅} ∈ Fin) → ((♯‘𝐴) = (♯‘{∅}) ↔ 𝐴 ≈ {∅})) | |
15 | 12, 13, 14 | sylancl 586 | . . . . 5 ⊢ ((𝐴 ∈ 𝑉 ∧ (♯‘𝐴) = (♯‘{∅})) → ((♯‘𝐴) = (♯‘{∅}) ↔ 𝐴 ≈ {∅})) |
16 | 7, 15 | mpbid 232 | . . . 4 ⊢ ((𝐴 ∈ 𝑉 ∧ (♯‘𝐴) = (♯‘{∅})) → 𝐴 ≈ {∅}) |
17 | 16 | ex 412 | . . 3 ⊢ (𝐴 ∈ 𝑉 → ((♯‘𝐴) = (♯‘{∅}) → 𝐴 ≈ {∅})) |
18 | hasheni 14384 | . . 3 ⊢ (𝐴 ≈ {∅} → (♯‘𝐴) = (♯‘{∅})) | |
19 | 17, 18 | impbid1 225 | . 2 ⊢ (𝐴 ∈ 𝑉 → ((♯‘𝐴) = (♯‘{∅}) ↔ 𝐴 ≈ {∅})) |
20 | df1o2 8512 | . . . . 5 ⊢ 1o = {∅} | |
21 | 20 | eqcomi 2744 | . . . 4 ⊢ {∅} = 1o |
22 | 21 | breq2i 5156 | . . 3 ⊢ (𝐴 ≈ {∅} ↔ 𝐴 ≈ 1o) |
23 | 22 | a1i 11 | . 2 ⊢ (𝐴 ∈ 𝑉 → (𝐴 ≈ {∅} ↔ 𝐴 ≈ 1o)) |
24 | 6, 19, 23 | 3bitrd 305 | 1 ⊢ (𝐴 ∈ 𝑉 → ((♯‘𝐴) = 1 ↔ 𝐴 ≈ 1o)) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ↔ wb 206 ∧ wa 395 = wceq 1537 ∈ wcel 2106 Vcvv 3478 ∅c0 4339 {csn 4631 class class class wbr 5148 ‘cfv 6563 1oc1o 8498 ≈ cen 8981 Fincfn 8984 1c1 11154 ℕ0cn0 12524 ♯chash 14366 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1792 ax-4 1806 ax-5 1908 ax-6 1965 ax-7 2005 ax-8 2108 ax-9 2116 ax-10 2139 ax-11 2155 ax-12 2175 ax-ext 2706 ax-sep 5302 ax-nul 5312 ax-pow 5371 ax-pr 5438 ax-un 7754 ax-cnex 11209 ax-resscn 11210 ax-1cn 11211 ax-icn 11212 ax-addcl 11213 ax-addrcl 11214 ax-mulcl 11215 ax-mulrcl 11216 ax-mulcom 11217 ax-addass 11218 ax-mulass 11219 ax-distr 11220 ax-i2m1 11221 ax-1ne0 11222 ax-1rid 11223 ax-rnegex 11224 ax-rrecex 11225 ax-cnre 11226 ax-pre-lttri 11227 ax-pre-lttrn 11228 ax-pre-ltadd 11229 ax-pre-mulgt0 11230 |
This theorem depends on definitions: df-bi 207 df-an 396 df-or 848 df-3or 1087 df-3an 1088 df-tru 1540 df-fal 1550 df-ex 1777 df-nf 1781 df-sb 2063 df-mo 2538 df-eu 2567 df-clab 2713 df-cleq 2727 df-clel 2814 df-nfc 2890 df-ne 2939 df-nel 3045 df-ral 3060 df-rex 3069 df-reu 3379 df-rab 3434 df-v 3480 df-sbc 3792 df-csb 3909 df-dif 3966 df-un 3968 df-in 3970 df-ss 3980 df-pss 3983 df-nul 4340 df-if 4532 df-pw 4607 df-sn 4632 df-pr 4634 df-op 4638 df-uni 4913 df-int 4952 df-iun 4998 df-br 5149 df-opab 5211 df-mpt 5232 df-tr 5266 df-id 5583 df-eprel 5589 df-po 5597 df-so 5598 df-fr 5641 df-we 5643 df-xp 5695 df-rel 5696 df-cnv 5697 df-co 5698 df-dm 5699 df-rn 5700 df-res 5701 df-ima 5702 df-pred 6323 df-ord 6389 df-on 6390 df-lim 6391 df-suc 6392 df-iota 6516 df-fun 6565 df-fn 6566 df-f 6567 df-f1 6568 df-fo 6569 df-f1o 6570 df-fv 6571 df-riota 7388 df-ov 7434 df-oprab 7435 df-mpo 7436 df-om 7888 df-1st 8013 df-2nd 8014 df-frecs 8305 df-wrecs 8336 df-recs 8410 df-rdg 8449 df-1o 8505 df-er 8744 df-en 8985 df-dom 8986 df-sdom 8987 df-fin 8988 df-card 9977 df-pnf 11295 df-mnf 11296 df-xr 11297 df-ltxr 11298 df-le 11299 df-sub 11492 df-neg 11493 df-nn 12265 df-n0 12525 df-z 12612 df-uz 12877 df-fz 13545 df-hash 14367 |
This theorem is referenced by: hash1elsn 14407 euhash1 14456 0ring 20543 0ring01eqbi 20549 lfuhgr3 35104 spthcycl 35114 |
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