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Mirrors > Home > MPE Home > Th. List > frgrwopregbsn | Structured version Visualization version GIF version |
Description: According to statement 5 in [Huneke] p. 2: "If ... B is a singleton, then that singleton is a universal friend". This version of frgrwopreg2 28258 is stricter (claiming that the singleton itself is a universal friend instead of claiming the existence of a universal friend only) and therefore closer to Huneke's statement. This strict variant, however, is not required for the proof of the friendship theorem. (Contributed 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 |
---|---|
frgrwopregbsn | ⊢ ((𝐺 ∈ FriendGraph ∧ 𝑋 ∈ 𝑉 ∧ 𝐵 = {𝑋}) → ∀𝑤 ∈ (𝑉 ∖ {𝑋}){𝑋, 𝑤} ∈ 𝐸) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | frgrwopreg.v | . . . 4 ⊢ 𝑉 = (Vtx‘𝐺) | |
2 | frgrwopreg.d | . . . 4 ⊢ 𝐷 = (VtxDeg‘𝐺) | |
3 | frgrwopreg.a | . . . 4 ⊢ 𝐴 = {𝑥 ∈ 𝑉 ∣ (𝐷‘𝑥) = 𝐾} | |
4 | frgrwopreg.b | . . . 4 ⊢ 𝐵 = (𝑉 ∖ 𝐴) | |
5 | frgrwopreg.e | . . . 4 ⊢ 𝐸 = (Edg‘𝐺) | |
6 | 1, 2, 3, 4, 5 | frgrwopreglem4 28254 | . . 3 ⊢ (𝐺 ∈ FriendGraph → ∀𝑤 ∈ 𝐴 ∀𝑣 ∈ 𝐵 {𝑤, 𝑣} ∈ 𝐸) |
7 | ralcom 3258 | . . . 4 ⊢ (∀𝑤 ∈ 𝐴 ∀𝑣 ∈ 𝐵 {𝑤, 𝑣} ∈ 𝐸 ↔ ∀𝑣 ∈ 𝐵 ∀𝑤 ∈ 𝐴 {𝑤, 𝑣} ∈ 𝐸) | |
8 | snidg 4550 | . . . . . . . 8 ⊢ (𝑋 ∈ 𝑉 → 𝑋 ∈ {𝑋}) | |
9 | 8 | adantr 484 | . . . . . . 7 ⊢ ((𝑋 ∈ 𝑉 ∧ 𝐵 = {𝑋}) → 𝑋 ∈ {𝑋}) |
10 | eleq2 2821 | . . . . . . . 8 ⊢ (𝐵 = {𝑋} → (𝑋 ∈ 𝐵 ↔ 𝑋 ∈ {𝑋})) | |
11 | 10 | adantl 485 | . . . . . . 7 ⊢ ((𝑋 ∈ 𝑉 ∧ 𝐵 = {𝑋}) → (𝑋 ∈ 𝐵 ↔ 𝑋 ∈ {𝑋})) |
12 | 9, 11 | mpbird 260 | . . . . . 6 ⊢ ((𝑋 ∈ 𝑉 ∧ 𝐵 = {𝑋}) → 𝑋 ∈ 𝐵) |
13 | preq2 4625 | . . . . . . . . . 10 ⊢ (𝑣 = 𝑋 → {𝑤, 𝑣} = {𝑤, 𝑋}) | |
14 | prcom 4623 | . . . . . . . . . 10 ⊢ {𝑤, 𝑋} = {𝑋, 𝑤} | |
15 | 13, 14 | eqtrdi 2789 | . . . . . . . . 9 ⊢ (𝑣 = 𝑋 → {𝑤, 𝑣} = {𝑋, 𝑤}) |
16 | 15 | eleq1d 2817 | . . . . . . . 8 ⊢ (𝑣 = 𝑋 → ({𝑤, 𝑣} ∈ 𝐸 ↔ {𝑋, 𝑤} ∈ 𝐸)) |
17 | 16 | ralbidv 3109 | . . . . . . 7 ⊢ (𝑣 = 𝑋 → (∀𝑤 ∈ 𝐴 {𝑤, 𝑣} ∈ 𝐸 ↔ ∀𝑤 ∈ 𝐴 {𝑋, 𝑤} ∈ 𝐸)) |
18 | 17 | rspcv 3521 | . . . . . 6 ⊢ (𝑋 ∈ 𝐵 → (∀𝑣 ∈ 𝐵 ∀𝑤 ∈ 𝐴 {𝑤, 𝑣} ∈ 𝐸 → ∀𝑤 ∈ 𝐴 {𝑋, 𝑤} ∈ 𝐸)) |
19 | 12, 18 | syl 17 | . . . . 5 ⊢ ((𝑋 ∈ 𝑉 ∧ 𝐵 = {𝑋}) → (∀𝑣 ∈ 𝐵 ∀𝑤 ∈ 𝐴 {𝑤, 𝑣} ∈ 𝐸 → ∀𝑤 ∈ 𝐴 {𝑋, 𝑤} ∈ 𝐸)) |
20 | 3 | ssrab3 3971 | . . . . . . . 8 ⊢ 𝐴 ⊆ 𝑉 |
21 | ssdifim 4153 | . . . . . . . 8 ⊢ ((𝐴 ⊆ 𝑉 ∧ 𝐵 = (𝑉 ∖ 𝐴)) → 𝐴 = (𝑉 ∖ 𝐵)) | |
22 | 20, 4, 21 | mp2an 692 | . . . . . . 7 ⊢ 𝐴 = (𝑉 ∖ 𝐵) |
23 | difeq2 4007 | . . . . . . . 8 ⊢ (𝐵 = {𝑋} → (𝑉 ∖ 𝐵) = (𝑉 ∖ {𝑋})) | |
24 | 23 | adantl 485 | . . . . . . 7 ⊢ ((𝑋 ∈ 𝑉 ∧ 𝐵 = {𝑋}) → (𝑉 ∖ 𝐵) = (𝑉 ∖ {𝑋})) |
25 | 22, 24 | syl5eq 2785 | . . . . . 6 ⊢ ((𝑋 ∈ 𝑉 ∧ 𝐵 = {𝑋}) → 𝐴 = (𝑉 ∖ {𝑋})) |
26 | 25 | raleqdv 3316 | . . . . 5 ⊢ ((𝑋 ∈ 𝑉 ∧ 𝐵 = {𝑋}) → (∀𝑤 ∈ 𝐴 {𝑋, 𝑤} ∈ 𝐸 ↔ ∀𝑤 ∈ (𝑉 ∖ {𝑋}){𝑋, 𝑤} ∈ 𝐸)) |
27 | 19, 26 | sylibd 242 | . . . 4 ⊢ ((𝑋 ∈ 𝑉 ∧ 𝐵 = {𝑋}) → (∀𝑣 ∈ 𝐵 ∀𝑤 ∈ 𝐴 {𝑤, 𝑣} ∈ 𝐸 → ∀𝑤 ∈ (𝑉 ∖ {𝑋}){𝑋, 𝑤} ∈ 𝐸)) |
28 | 7, 27 | syl5bi 245 | . . 3 ⊢ ((𝑋 ∈ 𝑉 ∧ 𝐵 = {𝑋}) → (∀𝑤 ∈ 𝐴 ∀𝑣 ∈ 𝐵 {𝑤, 𝑣} ∈ 𝐸 → ∀𝑤 ∈ (𝑉 ∖ {𝑋}){𝑋, 𝑤} ∈ 𝐸)) |
29 | 6, 28 | syl5com 31 | . 2 ⊢ (𝐺 ∈ FriendGraph → ((𝑋 ∈ 𝑉 ∧ 𝐵 = {𝑋}) → ∀𝑤 ∈ (𝑉 ∖ {𝑋}){𝑋, 𝑤} ∈ 𝐸)) |
30 | 29 | 3impib 1117 | 1 ⊢ ((𝐺 ∈ FriendGraph ∧ 𝑋 ∈ 𝑉 ∧ 𝐵 = {𝑋}) → ∀𝑤 ∈ (𝑉 ∖ {𝑋}){𝑋, 𝑤} ∈ 𝐸) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ↔ wb 209 ∧ wa 399 ∧ w3a 1088 = wceq 1542 ∈ wcel 2114 ∀wral 3053 {crab 3057 ∖ cdif 3840 ⊆ wss 3843 {csn 4516 {cpr 4518 ‘cfv 6339 Vtxcvtx 26943 Edgcedg 26994 VtxDegcvtxdg 27409 FriendGraph cfrgr 28197 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1802 ax-4 1816 ax-5 1917 ax-6 1975 ax-7 2020 ax-8 2116 ax-9 2124 ax-10 2145 ax-11 2162 ax-12 2179 ax-ext 2710 ax-rep 5154 ax-sep 5167 ax-nul 5174 ax-pow 5232 ax-pr 5296 ax-un 7481 ax-cnex 10673 ax-resscn 10674 ax-1cn 10675 ax-icn 10676 ax-addcl 10677 ax-addrcl 10678 ax-mulcl 10679 ax-mulrcl 10680 ax-mulcom 10681 ax-addass 10682 ax-mulass 10683 ax-distr 10684 ax-i2m1 10685 ax-1ne0 10686 ax-1rid 10687 ax-rnegex 10688 ax-rrecex 10689 ax-cnre 10690 ax-pre-lttri 10691 ax-pre-lttrn 10692 ax-pre-ltadd 10693 ax-pre-mulgt0 10694 |
This theorem depends on definitions: df-bi 210 df-an 400 df-or 847 df-3or 1089 df-3an 1090 df-tru 1545 df-fal 1555 df-ex 1787 df-nf 1791 df-sb 2075 df-mo 2540 df-eu 2570 df-clab 2717 df-cleq 2730 df-clel 2811 df-nfc 2881 df-ne 2935 df-nel 3039 df-ral 3058 df-rex 3059 df-reu 3060 df-rmo 3061 df-rab 3062 df-v 3400 df-sbc 3681 df-csb 3791 df-dif 3846 df-un 3848 df-in 3850 df-ss 3860 df-pss 3862 df-nul 4212 df-if 4415 df-pw 4490 df-sn 4517 df-pr 4519 df-tp 4521 df-op 4523 df-uni 4797 df-int 4837 df-iun 4883 df-br 5031 df-opab 5093 df-mpt 5111 df-tr 5137 df-id 5429 df-eprel 5434 df-po 5442 df-so 5443 df-fr 5483 df-we 5485 df-xp 5531 df-rel 5532 df-cnv 5533 df-co 5534 df-dm 5535 df-rn 5536 df-res 5537 df-ima 5538 df-pred 6129 df-ord 6175 df-on 6176 df-lim 6177 df-suc 6178 df-iota 6297 df-fun 6341 df-fn 6342 df-f 6343 df-f1 6344 df-fo 6345 df-f1o 6346 df-fv 6347 df-riota 7129 df-ov 7175 df-oprab 7176 df-mpo 7177 df-om 7602 df-1st 7716 df-2nd 7717 df-wrecs 7978 df-recs 8039 df-rdg 8077 df-1o 8133 df-2o 8134 df-oadd 8137 df-er 8322 df-en 8558 df-dom 8559 df-sdom 8560 df-fin 8561 df-dju 9405 df-card 9443 df-pnf 10757 df-mnf 10758 df-xr 10759 df-ltxr 10760 df-le 10761 df-sub 10952 df-neg 10953 df-nn 11719 df-2 11781 df-n0 11979 df-xnn0 12051 df-z 12065 df-uz 12327 df-xadd 12593 df-fz 12984 df-hash 13785 df-edg 26995 df-uhgr 27005 df-ushgr 27006 df-upgr 27029 df-umgr 27030 df-uspgr 27097 df-usgr 27098 df-nbgr 27277 df-vtxdg 27410 df-frgr 28198 |
This theorem is referenced by: frgrwopreg2 28258 |
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