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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 6670 | . . . . 5 ⊢ 𝑉 ∈ V |
4 | 1, 3 | rabex2 5223 | . . . 4 ⊢ 𝐴 ∈ V |
5 | hash1snb 13770 | . . . 4 ⊢ (𝐴 ∈ V → ((♯‘𝐴) = 1 ↔ ∃𝑣 𝐴 = {𝑣})) | |
6 | 4, 5 | ax-mp 5 | . . 3 ⊢ ((♯‘𝐴) = 1 ↔ ∃𝑣 𝐴 = {𝑣}) |
7 | exsnrex 4604 | . . . . 5 ⊢ (∃𝑣 𝐴 = {𝑣} ↔ ∃𝑣 ∈ 𝐴 𝐴 = {𝑣}) | |
8 | 1 | ssrab3 4045 | . . . . . . 7 ⊢ 𝐴 ⊆ 𝑉 |
9 | ssrexv 4022 | . . . . . . 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 28079 | . . . . . . . 8 ⊢ ((𝐺 ∈ FriendGraph ∧ 𝑣 ∈ 𝑉 ∧ 𝐴 = {𝑣}) → ∀𝑤 ∈ (𝑉 ∖ {𝑣}){𝑣, 𝑤} ∈ 𝐸) |
15 | 14 | 3expia 1117 | . . . . . . 7 ⊢ ((𝐺 ∈ FriendGraph ∧ 𝑣 ∈ 𝑉) → (𝐴 = {𝑣} → ∀𝑤 ∈ (𝑉 ∖ {𝑣}){𝑣, 𝑤} ∈ 𝐸)) |
16 | 15 | reximdva 3274 | . . . . . 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 219 | . . . 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 244 | . 2 ⊢ (𝐺 ∈ FriendGraph → ((♯‘𝐴) = 1 → ∃𝑣 ∈ 𝑉 ∀𝑤 ∈ (𝑉 ∖ {𝑣}){𝑣, 𝑤} ∈ 𝐸)) |
21 | 20 | imp 409 | 1 ⊢ ((𝐺 ∈ FriendGraph ∧ (♯‘𝐴) = 1) → ∃𝑣 ∈ 𝑉 ∀𝑤 ∈ (𝑉 ∖ {𝑣}){𝑣, 𝑤} ∈ 𝐸) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ↔ wb 208 ∧ wa 398 = wceq 1537 ∃wex 1780 ∈ wcel 2114 ∀wral 3138 ∃wrex 3139 {crab 3142 Vcvv 3486 ∖ cdif 3921 ⊆ wss 3924 {csn 4553 {cpr 4555 ‘cfv 6341 1c1 10524 ♯chash 13680 Vtxcvtx 26767 Edgcedg 26818 VtxDegcvtxdg 27233 FriendGraph cfrgr 28021 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1796 ax-4 1810 ax-5 1911 ax-6 1970 ax-7 2015 ax-8 2116 ax-9 2124 ax-10 2145 ax-11 2161 ax-12 2177 ax-ext 2793 ax-rep 5176 ax-sep 5189 ax-nul 5196 ax-pow 5252 ax-pr 5316 ax-un 7447 ax-cnex 10579 ax-resscn 10580 ax-1cn 10581 ax-icn 10582 ax-addcl 10583 ax-addrcl 10584 ax-mulcl 10585 ax-mulrcl 10586 ax-mulcom 10587 ax-addass 10588 ax-mulass 10589 ax-distr 10590 ax-i2m1 10591 ax-1ne0 10592 ax-1rid 10593 ax-rnegex 10594 ax-rrecex 10595 ax-cnre 10596 ax-pre-lttri 10597 ax-pre-lttrn 10598 ax-pre-ltadd 10599 ax-pre-mulgt0 10600 |
This theorem depends on definitions: df-bi 209 df-an 399 df-or 844 df-3or 1084 df-3an 1085 df-tru 1540 df-fal 1550 df-ex 1781 df-nf 1785 df-sb 2070 df-mo 2622 df-eu 2654 df-clab 2800 df-cleq 2814 df-clel 2893 df-nfc 2963 df-ne 3017 df-nel 3124 df-ral 3143 df-rex 3144 df-reu 3145 df-rmo 3146 df-rab 3147 df-v 3488 df-sbc 3764 df-csb 3872 df-dif 3927 df-un 3929 df-in 3931 df-ss 3940 df-pss 3942 df-nul 4280 df-if 4454 df-pw 4527 df-sn 4554 df-pr 4556 df-tp 4558 df-op 4560 df-uni 4825 df-int 4863 df-iun 4907 df-br 5053 df-opab 5115 df-mpt 5133 df-tr 5159 df-id 5446 df-eprel 5451 df-po 5460 df-so 5461 df-fr 5500 df-we 5502 df-xp 5547 df-rel 5548 df-cnv 5549 df-co 5550 df-dm 5551 df-rn 5552 df-res 5553 df-ima 5554 df-pred 6134 df-ord 6180 df-on 6181 df-lim 6182 df-suc 6183 df-iota 6300 df-fun 6343 df-fn 6344 df-f 6345 df-f1 6346 df-fo 6347 df-f1o 6348 df-fv 6349 df-riota 7100 df-ov 7145 df-oprab 7146 df-mpo 7147 df-om 7567 df-1st 7675 df-2nd 7676 df-wrecs 7933 df-recs 7994 df-rdg 8032 df-1o 8088 df-2o 8089 df-oadd 8092 df-er 8275 df-en 8496 df-dom 8497 df-sdom 8498 df-fin 8499 df-dju 9316 df-card 9354 df-pnf 10663 df-mnf 10664 df-xr 10665 df-ltxr 10666 df-le 10667 df-sub 10858 df-neg 10859 df-nn 11625 df-2 11687 df-n0 11885 df-xnn0 11955 df-z 11969 df-uz 12231 df-xadd 12495 df-fz 12883 df-hash 13681 df-edg 26819 df-uhgr 26829 df-ushgr 26830 df-upgr 26853 df-umgr 26854 df-uspgr 26921 df-usgr 26922 df-nbgr 27101 df-vtxdg 27234 df-frgr 28022 |
This theorem is referenced by: frgrregorufr0 28087 |
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