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Mirrors > Home > MPE Home > Th. List > frgrwopreg1 | Structured version Visualization version GIF version |
Description: According to statement 5 in [Huneke] p. 2: "If A ... is a singleton, then that singleton is a universal friend". (Contributed by Alexander van der Vekens, 1-Jan-2018.) (Proof shortened by AV, 4-Feb-2022.) |
Ref | Expression |
---|---|
frgrwopreg.v | ⊢ 𝑉 = (Vtx‘𝐺) |
frgrwopreg.d | ⊢ 𝐷 = (VtxDeg‘𝐺) |
frgrwopreg.a | ⊢ 𝐴 = {𝑥 ∈ 𝑉 ∣ (𝐷‘𝑥) = 𝐾} |
frgrwopreg.b | ⊢ 𝐵 = (𝑉 ∖ 𝐴) |
frgrwopreg.e | ⊢ 𝐸 = (Edg‘𝐺) |
Ref | Expression |
---|---|
frgrwopreg1 | ⊢ ((𝐺 ∈ FriendGraph ∧ (♯‘𝐴) = 1) → ∃𝑣 ∈ 𝑉 ∀𝑤 ∈ (𝑉 ∖ {𝑣}){𝑣, 𝑤} ∈ 𝐸) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | frgrwopreg.a | . . . . 5 ⊢ 𝐴 = {𝑥 ∈ 𝑉 ∣ (𝐷‘𝑥) = 𝐾} | |
2 | frgrwopreg.v | . . . . . 6 ⊢ 𝑉 = (Vtx‘𝐺) | |
3 | 2 | fvexi 6518 | . . . . 5 ⊢ 𝑉 ∈ V |
4 | 1, 3 | rabex2 5097 | . . . 4 ⊢ 𝐴 ∈ V |
5 | hash1snb 13599 | . . . 4 ⊢ (𝐴 ∈ V → ((♯‘𝐴) = 1 ↔ ∃𝑣 𝐴 = {𝑣})) | |
6 | 4, 5 | ax-mp 5 | . . 3 ⊢ ((♯‘𝐴) = 1 ↔ ∃𝑣 𝐴 = {𝑣}) |
7 | exsnrex 4497 | . . . . 5 ⊢ (∃𝑣 𝐴 = {𝑣} ↔ ∃𝑣 ∈ 𝐴 𝐴 = {𝑣}) | |
8 | 1 | ssrab3 3949 | . . . . . . 7 ⊢ 𝐴 ⊆ 𝑉 |
9 | ssrexv 3926 | . . . . . . 7 ⊢ (𝐴 ⊆ 𝑉 → (∃𝑣 ∈ 𝐴 𝐴 = {𝑣} → ∃𝑣 ∈ 𝑉 𝐴 = {𝑣})) | |
10 | 8, 9 | ax-mp 5 | . . . . . 6 ⊢ (∃𝑣 ∈ 𝐴 𝐴 = {𝑣} → ∃𝑣 ∈ 𝑉 𝐴 = {𝑣}) |
11 | frgrwopreg.d | . . . . . . . . 9 ⊢ 𝐷 = (VtxDeg‘𝐺) | |
12 | frgrwopreg.b | . . . . . . . . 9 ⊢ 𝐵 = (𝑉 ∖ 𝐴) | |
13 | frgrwopreg.e | . . . . . . . . 9 ⊢ 𝐸 = (Edg‘𝐺) | |
14 | 2, 11, 1, 12, 13 | frgrwopregasn 27865 | . . . . . . . 8 ⊢ ((𝐺 ∈ FriendGraph ∧ 𝑣 ∈ 𝑉 ∧ 𝐴 = {𝑣}) → ∀𝑤 ∈ (𝑉 ∖ {𝑣}){𝑣, 𝑤} ∈ 𝐸) |
15 | 14 | 3expia 1102 | . . . . . . 7 ⊢ ((𝐺 ∈ FriendGraph ∧ 𝑣 ∈ 𝑉) → (𝐴 = {𝑣} → ∀𝑤 ∈ (𝑉 ∖ {𝑣}){𝑣, 𝑤} ∈ 𝐸)) |
16 | 15 | reximdva 3221 | . . . . . 6 ⊢ (𝐺 ∈ FriendGraph → (∃𝑣 ∈ 𝑉 𝐴 = {𝑣} → ∃𝑣 ∈ 𝑉 ∀𝑤 ∈ (𝑉 ∖ {𝑣}){𝑣, 𝑤} ∈ 𝐸)) |
17 | 10, 16 | syl5com 31 | . . . . 5 ⊢ (∃𝑣 ∈ 𝐴 𝐴 = {𝑣} → (𝐺 ∈ FriendGraph → ∃𝑣 ∈ 𝑉 ∀𝑤 ∈ (𝑉 ∖ {𝑣}){𝑣, 𝑤} ∈ 𝐸)) |
18 | 7, 17 | sylbi 209 | . . . 4 ⊢ (∃𝑣 𝐴 = {𝑣} → (𝐺 ∈ FriendGraph → ∃𝑣 ∈ 𝑉 ∀𝑤 ∈ (𝑉 ∖ {𝑣}){𝑣, 𝑤} ∈ 𝐸)) |
19 | 18 | com12 32 | . . 3 ⊢ (𝐺 ∈ FriendGraph → (∃𝑣 𝐴 = {𝑣} → ∃𝑣 ∈ 𝑉 ∀𝑤 ∈ (𝑉 ∖ {𝑣}){𝑣, 𝑤} ∈ 𝐸)) |
20 | 6, 19 | syl5bi 234 | . 2 ⊢ (𝐺 ∈ FriendGraph → ((♯‘𝐴) = 1 → ∃𝑣 ∈ 𝑉 ∀𝑤 ∈ (𝑉 ∖ {𝑣}){𝑣, 𝑤} ∈ 𝐸)) |
21 | 20 | imp 398 | 1 ⊢ ((𝐺 ∈ FriendGraph ∧ (♯‘𝐴) = 1) → ∃𝑣 ∈ 𝑉 ∀𝑤 ∈ (𝑉 ∖ {𝑣}){𝑣, 𝑤} ∈ 𝐸) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ↔ wb 198 ∧ wa 387 = wceq 1508 ∃wex 1743 ∈ wcel 2051 ∀wral 3090 ∃wrex 3091 {crab 3094 Vcvv 3417 ∖ cdif 3828 ⊆ wss 3831 {csn 4444 {cpr 4446 ‘cfv 6193 1c1 10342 ♯chash 13511 Vtxcvtx 26499 Edgcedg 26550 VtxDegcvtxdg 26965 FriendGraph cfrgr 27805 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1759 ax-4 1773 ax-5 1870 ax-6 1929 ax-7 1966 ax-8 2053 ax-9 2060 ax-10 2080 ax-11 2094 ax-12 2107 ax-13 2302 ax-ext 2752 ax-rep 5053 ax-sep 5064 ax-nul 5071 ax-pow 5123 ax-pr 5190 ax-un 7285 ax-cnex 10397 ax-resscn 10398 ax-1cn 10399 ax-icn 10400 ax-addcl 10401 ax-addrcl 10402 ax-mulcl 10403 ax-mulrcl 10404 ax-mulcom 10405 ax-addass 10406 ax-mulass 10407 ax-distr 10408 ax-i2m1 10409 ax-1ne0 10410 ax-1rid 10411 ax-rnegex 10412 ax-rrecex 10413 ax-cnre 10414 ax-pre-lttri 10415 ax-pre-lttrn 10416 ax-pre-ltadd 10417 ax-pre-mulgt0 10418 |
This theorem depends on definitions: df-bi 199 df-an 388 df-or 835 df-3or 1070 df-3an 1071 df-tru 1511 df-fal 1521 df-ex 1744 df-nf 1748 df-sb 2017 df-mo 2551 df-eu 2589 df-clab 2761 df-cleq 2773 df-clel 2848 df-nfc 2920 df-ne 2970 df-nel 3076 df-ral 3095 df-rex 3096 df-reu 3097 df-rmo 3098 df-rab 3099 df-v 3419 df-sbc 3684 df-csb 3789 df-dif 3834 df-un 3836 df-in 3838 df-ss 3845 df-pss 3847 df-nul 4182 df-if 4354 df-pw 4427 df-sn 4445 df-pr 4447 df-tp 4449 df-op 4451 df-uni 4718 df-int 4755 df-iun 4799 df-br 4935 df-opab 4997 df-mpt 5014 df-tr 5036 df-id 5316 df-eprel 5321 df-po 5330 df-so 5331 df-fr 5370 df-we 5372 df-xp 5417 df-rel 5418 df-cnv 5419 df-co 5420 df-dm 5421 df-rn 5422 df-res 5423 df-ima 5424 df-pred 5991 df-ord 6037 df-on 6038 df-lim 6039 df-suc 6040 df-iota 6157 df-fun 6195 df-fn 6196 df-f 6197 df-f1 6198 df-fo 6199 df-f1o 6200 df-fv 6201 df-riota 6943 df-ov 6985 df-oprab 6986 df-mpo 6987 df-om 7403 df-1st 7507 df-2nd 7508 df-wrecs 7756 df-recs 7818 df-rdg 7856 df-1o 7911 df-2o 7912 df-oadd 7915 df-er 8095 df-en 8313 df-dom 8314 df-sdom 8315 df-fin 8316 df-dju 9130 df-card 9168 df-pnf 10482 df-mnf 10483 df-xr 10484 df-ltxr 10485 df-le 10486 df-sub 10678 df-neg 10679 df-nn 11446 df-2 11509 df-n0 11714 df-xnn0 11786 df-z 11800 df-uz 12065 df-xadd 12331 df-fz 12715 df-hash 13512 df-edg 26551 df-uhgr 26561 df-ushgr 26562 df-upgr 26585 df-umgr 26586 df-uspgr 26653 df-usgr 26654 df-nbgr 26833 df-vtxdg 26966 df-frgr 27806 |
This theorem is referenced by: frgrregorufr0 27873 |
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