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Mirrors > Home > MPE Home > Th. List > hash1snb | Structured version Visualization version GIF version |
Description: The size of a set is 1 if and only if it is a singleton (containing a set). (Contributed by Alexander van der Vekens, 7-Dec-2017.) |
Ref | Expression |
---|---|
hash1snb | ⊢ (𝑉 ∈ 𝑊 → ((♯‘𝑉) = 1 ↔ ∃𝑎 𝑉 = {𝑎})) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | id 22 | . . . . . . . . 9 ⊢ ((♯‘𝑉) = 1 → (♯‘𝑉) = 1) | |
2 | hash1 14366 | . . . . . . . . 9 ⊢ (♯‘1o) = 1 | |
3 | 1, 2 | eqtr4di 2790 | . . . . . . . 8 ⊢ ((♯‘𝑉) = 1 → (♯‘𝑉) = (♯‘1o)) |
4 | 3 | adantl 482 | . . . . . . 7 ⊢ ((𝑉 ∈ Fin ∧ (♯‘𝑉) = 1) → (♯‘𝑉) = (♯‘1o)) |
5 | 1onn 8641 | . . . . . . . . 9 ⊢ 1o ∈ ω | |
6 | nnfi 9169 | . . . . . . . . 9 ⊢ (1o ∈ ω → 1o ∈ Fin) | |
7 | 5, 6 | mp1i 13 | . . . . . . . 8 ⊢ ((♯‘𝑉) = 1 → 1o ∈ Fin) |
8 | hashen 14309 | . . . . . . . 8 ⊢ ((𝑉 ∈ Fin ∧ 1o ∈ Fin) → ((♯‘𝑉) = (♯‘1o) ↔ 𝑉 ≈ 1o)) | |
9 | 7, 8 | sylan2 593 | . . . . . . 7 ⊢ ((𝑉 ∈ Fin ∧ (♯‘𝑉) = 1) → ((♯‘𝑉) = (♯‘1o) ↔ 𝑉 ≈ 1o)) |
10 | 4, 9 | mpbid 231 | . . . . . 6 ⊢ ((𝑉 ∈ Fin ∧ (♯‘𝑉) = 1) → 𝑉 ≈ 1o) |
11 | en1 9023 | . . . . . 6 ⊢ (𝑉 ≈ 1o ↔ ∃𝑎 𝑉 = {𝑎}) | |
12 | 10, 11 | sylib 217 | . . . . 5 ⊢ ((𝑉 ∈ Fin ∧ (♯‘𝑉) = 1) → ∃𝑎 𝑉 = {𝑎}) |
13 | 12 | ex 413 | . . . 4 ⊢ (𝑉 ∈ Fin → ((♯‘𝑉) = 1 → ∃𝑎 𝑉 = {𝑎})) |
14 | 13 | a1d 25 | . . 3 ⊢ (𝑉 ∈ Fin → (𝑉 ∈ 𝑊 → ((♯‘𝑉) = 1 → ∃𝑎 𝑉 = {𝑎}))) |
15 | hashinf 14297 | . . . . 5 ⊢ ((𝑉 ∈ 𝑊 ∧ ¬ 𝑉 ∈ Fin) → (♯‘𝑉) = +∞) | |
16 | eqeq1 2736 | . . . . . 6 ⊢ ((♯‘𝑉) = +∞ → ((♯‘𝑉) = 1 ↔ +∞ = 1)) | |
17 | 1re 11216 | . . . . . . . 8 ⊢ 1 ∈ ℝ | |
18 | renepnf 11264 | . . . . . . . 8 ⊢ (1 ∈ ℝ → 1 ≠ +∞) | |
19 | df-ne 2941 | . . . . . . . . 9 ⊢ (1 ≠ +∞ ↔ ¬ 1 = +∞) | |
20 | pm2.21 123 | . . . . . . . . 9 ⊢ (¬ 1 = +∞ → (1 = +∞ → ∃𝑎 𝑉 = {𝑎})) | |
21 | 19, 20 | sylbi 216 | . . . . . . . 8 ⊢ (1 ≠ +∞ → (1 = +∞ → ∃𝑎 𝑉 = {𝑎})) |
22 | 17, 18, 21 | mp2b 10 | . . . . . . 7 ⊢ (1 = +∞ → ∃𝑎 𝑉 = {𝑎}) |
23 | 22 | eqcoms 2740 | . . . . . 6 ⊢ (+∞ = 1 → ∃𝑎 𝑉 = {𝑎}) |
24 | 16, 23 | syl6bi 252 | . . . . 5 ⊢ ((♯‘𝑉) = +∞ → ((♯‘𝑉) = 1 → ∃𝑎 𝑉 = {𝑎})) |
25 | 15, 24 | syl 17 | . . . 4 ⊢ ((𝑉 ∈ 𝑊 ∧ ¬ 𝑉 ∈ Fin) → ((♯‘𝑉) = 1 → ∃𝑎 𝑉 = {𝑎})) |
26 | 25 | expcom 414 | . . 3 ⊢ (¬ 𝑉 ∈ Fin → (𝑉 ∈ 𝑊 → ((♯‘𝑉) = 1 → ∃𝑎 𝑉 = {𝑎}))) |
27 | 14, 26 | pm2.61i 182 | . 2 ⊢ (𝑉 ∈ 𝑊 → ((♯‘𝑉) = 1 → ∃𝑎 𝑉 = {𝑎})) |
28 | fveq2 6891 | . . . 4 ⊢ (𝑉 = {𝑎} → (♯‘𝑉) = (♯‘{𝑎})) | |
29 | hashsng 14331 | . . . . 5 ⊢ (𝑎 ∈ V → (♯‘{𝑎}) = 1) | |
30 | 29 | elv 3480 | . . . 4 ⊢ (♯‘{𝑎}) = 1 |
31 | 28, 30 | eqtrdi 2788 | . . 3 ⊢ (𝑉 = {𝑎} → (♯‘𝑉) = 1) |
32 | 31 | exlimiv 1933 | . 2 ⊢ (∃𝑎 𝑉 = {𝑎} → (♯‘𝑉) = 1) |
33 | 27, 32 | impbid1 224 | 1 ⊢ (𝑉 ∈ 𝑊 → ((♯‘𝑉) = 1 ↔ ∃𝑎 𝑉 = {𝑎})) |
Colors of variables: wff setvar class |
Syntax hints: ¬ wn 3 → wi 4 ↔ wb 205 ∧ wa 396 = wceq 1541 ∃wex 1781 ∈ wcel 2106 ≠ wne 2940 Vcvv 3474 {csn 4628 class class class wbr 5148 ‘cfv 6543 ωcom 7857 1oc1o 8461 ≈ cen 8938 Fincfn 8941 ℝcr 11111 1c1 11113 +∞cpnf 11247 ♯chash 14292 |
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 1913 ax-6 1971 ax-7 2011 ax-8 2108 ax-9 2116 ax-10 2137 ax-11 2154 ax-12 2171 ax-ext 2703 ax-sep 5299 ax-nul 5306 ax-pow 5363 ax-pr 5427 ax-un 7727 ax-cnex 11168 ax-resscn 11169 ax-1cn 11170 ax-icn 11171 ax-addcl 11172 ax-addrcl 11173 ax-mulcl 11174 ax-mulrcl 11175 ax-mulcom 11176 ax-addass 11177 ax-mulass 11178 ax-distr 11179 ax-i2m1 11180 ax-1ne0 11181 ax-1rid 11182 ax-rnegex 11183 ax-rrecex 11184 ax-cnre 11185 ax-pre-lttri 11186 ax-pre-lttrn 11187 ax-pre-ltadd 11188 ax-pre-mulgt0 11189 |
This theorem depends on definitions: df-bi 206 df-an 397 df-or 846 df-3or 1088 df-3an 1089 df-tru 1544 df-fal 1554 df-ex 1782 df-nf 1786 df-sb 2068 df-mo 2534 df-eu 2563 df-clab 2710 df-cleq 2724 df-clel 2810 df-nfc 2885 df-ne 2941 df-nel 3047 df-ral 3062 df-rex 3071 df-reu 3377 df-rab 3433 df-v 3476 df-sbc 3778 df-csb 3894 df-dif 3951 df-un 3953 df-in 3955 df-ss 3965 df-pss 3967 df-nul 4323 df-if 4529 df-pw 4604 df-sn 4629 df-pr 4631 df-op 4635 df-uni 4909 df-int 4951 df-iun 4999 df-br 5149 df-opab 5211 df-mpt 5232 df-tr 5266 df-id 5574 df-eprel 5580 df-po 5588 df-so 5589 df-fr 5631 df-we 5633 df-xp 5682 df-rel 5683 df-cnv 5684 df-co 5685 df-dm 5686 df-rn 5687 df-res 5688 df-ima 5689 df-pred 6300 df-ord 6367 df-on 6368 df-lim 6369 df-suc 6370 df-iota 6495 df-fun 6545 df-fn 6546 df-f 6547 df-f1 6548 df-fo 6549 df-f1o 6550 df-fv 6551 df-riota 7367 df-ov 7414 df-oprab 7415 df-mpo 7416 df-om 7858 df-1st 7977 df-2nd 7978 df-frecs 8268 df-wrecs 8299 df-recs 8373 df-rdg 8412 df-1o 8468 df-oadd 8472 df-er 8705 df-en 8942 df-dom 8943 df-sdom 8944 df-fin 8945 df-dju 9898 df-card 9936 df-pnf 11252 df-mnf 11253 df-xr 11254 df-ltxr 11255 df-le 11256 df-sub 11448 df-neg 11449 df-nn 12215 df-n0 12475 df-z 12561 df-uz 12825 df-fz 13487 df-hash 14293 |
This theorem is referenced by: hash1n0 14383 hashle2pr 14440 hashge2el2difr 14444 hash1to3 14454 cshwrepswhash1 17038 symgvalstruct 19266 symgvalstructOLD 19267 mat1scmat 22048 tgldim0eq 27792 lfuhgr1v0e 28549 usgr1v0e 28621 nbgr1vtx 28653 uvtx01vtx 28692 cplgr1vlem 28724 cplgr1v 28725 1loopgrvd2 28798 vdgn1frgrv2 29587 frgrwopreg1 29609 frgrwopreg2 29610 extdg1id 32801 c0snmgmhm 46792 |
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