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| Mirrors > Home > MPE Home > Th. List > frgrwopregasn | 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". This version of frgrwopreg1 30337 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 Alexander van der Vekens, 1-Jan-2018.) (Revised 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 |
|---|---|
| frgrwopregasn | ⊢ ((𝐺 ∈ FriendGraph ∧ 𝑋 ∈ 𝑉 ∧ 𝐴 = {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 30334 | . . 3 ⊢ (𝐺 ∈ FriendGraph → ∀𝑣 ∈ 𝐴 ∀𝑤 ∈ 𝐵 {𝑣, 𝑤} ∈ 𝐸) |
| 7 | snidg 4660 | . . . . . . 7 ⊢ (𝑋 ∈ 𝑉 → 𝑋 ∈ {𝑋}) | |
| 8 | 7 | adantr 480 | . . . . . 6 ⊢ ((𝑋 ∈ 𝑉 ∧ 𝐴 = {𝑋}) → 𝑋 ∈ {𝑋}) |
| 9 | eleq2 2830 | . . . . . . 7 ⊢ (𝐴 = {𝑋} → (𝑋 ∈ 𝐴 ↔ 𝑋 ∈ {𝑋})) | |
| 10 | 9 | adantl 481 | . . . . . 6 ⊢ ((𝑋 ∈ 𝑉 ∧ 𝐴 = {𝑋}) → (𝑋 ∈ 𝐴 ↔ 𝑋 ∈ {𝑋})) |
| 11 | 8, 10 | mpbird 257 | . . . . 5 ⊢ ((𝑋 ∈ 𝑉 ∧ 𝐴 = {𝑋}) → 𝑋 ∈ 𝐴) |
| 12 | preq1 4733 | . . . . . . . 8 ⊢ (𝑣 = 𝑋 → {𝑣, 𝑤} = {𝑋, 𝑤}) | |
| 13 | 12 | eleq1d 2826 | . . . . . . 7 ⊢ (𝑣 = 𝑋 → ({𝑣, 𝑤} ∈ 𝐸 ↔ {𝑋, 𝑤} ∈ 𝐸)) |
| 14 | 13 | ralbidv 3178 | . . . . . 6 ⊢ (𝑣 = 𝑋 → (∀𝑤 ∈ 𝐵 {𝑣, 𝑤} ∈ 𝐸 ↔ ∀𝑤 ∈ 𝐵 {𝑋, 𝑤} ∈ 𝐸)) |
| 15 | 14 | rspcv 3618 | . . . . 5 ⊢ (𝑋 ∈ 𝐴 → (∀𝑣 ∈ 𝐴 ∀𝑤 ∈ 𝐵 {𝑣, 𝑤} ∈ 𝐸 → ∀𝑤 ∈ 𝐵 {𝑋, 𝑤} ∈ 𝐸)) |
| 16 | 11, 15 | syl 17 | . . . 4 ⊢ ((𝑋 ∈ 𝑉 ∧ 𝐴 = {𝑋}) → (∀𝑣 ∈ 𝐴 ∀𝑤 ∈ 𝐵 {𝑣, 𝑤} ∈ 𝐸 → ∀𝑤 ∈ 𝐵 {𝑋, 𝑤} ∈ 𝐸)) |
| 17 | difeq2 4120 | . . . . . . 7 ⊢ (𝐴 = {𝑋} → (𝑉 ∖ 𝐴) = (𝑉 ∖ {𝑋})) | |
| 18 | 4, 17 | eqtrid 2789 | . . . . . 6 ⊢ (𝐴 = {𝑋} → 𝐵 = (𝑉 ∖ {𝑋})) |
| 19 | 18 | adantl 481 | . . . . 5 ⊢ ((𝑋 ∈ 𝑉 ∧ 𝐴 = {𝑋}) → 𝐵 = (𝑉 ∖ {𝑋})) |
| 20 | 19 | raleqdv 3326 | . . . 4 ⊢ ((𝑋 ∈ 𝑉 ∧ 𝐴 = {𝑋}) → (∀𝑤 ∈ 𝐵 {𝑋, 𝑤} ∈ 𝐸 ↔ ∀𝑤 ∈ (𝑉 ∖ {𝑋}){𝑋, 𝑤} ∈ 𝐸)) |
| 21 | 16, 20 | sylibd 239 | . . 3 ⊢ ((𝑋 ∈ 𝑉 ∧ 𝐴 = {𝑋}) → (∀𝑣 ∈ 𝐴 ∀𝑤 ∈ 𝐵 {𝑣, 𝑤} ∈ 𝐸 → ∀𝑤 ∈ (𝑉 ∖ {𝑋}){𝑋, 𝑤} ∈ 𝐸)) |
| 22 | 6, 21 | syl5com 31 | . 2 ⊢ (𝐺 ∈ FriendGraph → ((𝑋 ∈ 𝑉 ∧ 𝐴 = {𝑋}) → ∀𝑤 ∈ (𝑉 ∖ {𝑋}){𝑋, 𝑤} ∈ 𝐸)) |
| 23 | 22 | 3impib 1117 | 1 ⊢ ((𝐺 ∈ FriendGraph ∧ 𝑋 ∈ 𝑉 ∧ 𝐴 = {𝑋}) → ∀𝑤 ∈ (𝑉 ∖ {𝑋}){𝑋, 𝑤} ∈ 𝐸) |
| Colors of variables: wff setvar class |
| Syntax hints: → wi 4 ↔ wb 206 ∧ wa 395 ∧ w3a 1087 = wceq 1540 ∈ wcel 2108 ∀wral 3061 {crab 3436 ∖ cdif 3948 {csn 4626 {cpr 4628 ‘cfv 6561 Vtxcvtx 29013 Edgcedg 29064 VtxDegcvtxdg 29483 FriendGraph cfrgr 30277 |
| This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1795 ax-4 1809 ax-5 1910 ax-6 1967 ax-7 2007 ax-8 2110 ax-9 2118 ax-10 2141 ax-11 2157 ax-12 2177 ax-ext 2708 ax-rep 5279 ax-sep 5296 ax-nul 5306 ax-pow 5365 ax-pr 5432 ax-un 7755 ax-cnex 11211 ax-resscn 11212 ax-1cn 11213 ax-icn 11214 ax-addcl 11215 ax-addrcl 11216 ax-mulcl 11217 ax-mulrcl 11218 ax-mulcom 11219 ax-addass 11220 ax-mulass 11221 ax-distr 11222 ax-i2m1 11223 ax-1ne0 11224 ax-1rid 11225 ax-rnegex 11226 ax-rrecex 11227 ax-cnre 11228 ax-pre-lttri 11229 ax-pre-lttrn 11230 ax-pre-ltadd 11231 ax-pre-mulgt0 11232 |
| This theorem depends on definitions: df-bi 207 df-an 396 df-or 849 df-3or 1088 df-3an 1089 df-tru 1543 df-fal 1553 df-ex 1780 df-nf 1784 df-sb 2065 df-mo 2540 df-eu 2569 df-clab 2715 df-cleq 2729 df-clel 2816 df-nfc 2892 df-ne 2941 df-nel 3047 df-ral 3062 df-rex 3071 df-rmo 3380 df-reu 3381 df-rab 3437 df-v 3482 df-sbc 3789 df-csb 3900 df-dif 3954 df-un 3956 df-in 3958 df-ss 3968 df-pss 3971 df-nul 4334 df-if 4526 df-pw 4602 df-sn 4627 df-pr 4629 df-op 4633 df-uni 4908 df-int 4947 df-iun 4993 df-br 5144 df-opab 5206 df-mpt 5226 df-tr 5260 df-id 5578 df-eprel 5584 df-po 5592 df-so 5593 df-fr 5637 df-we 5639 df-xp 5691 df-rel 5692 df-cnv 5693 df-co 5694 df-dm 5695 df-rn 5696 df-res 5697 df-ima 5698 df-pred 6321 df-ord 6387 df-on 6388 df-lim 6389 df-suc 6390 df-iota 6514 df-fun 6563 df-fn 6564 df-f 6565 df-f1 6566 df-fo 6567 df-f1o 6568 df-fv 6569 df-riota 7388 df-ov 7434 df-oprab 7435 df-mpo 7436 df-om 7888 df-1st 8014 df-2nd 8015 df-frecs 8306 df-wrecs 8337 df-recs 8411 df-rdg 8450 df-1o 8506 df-2o 8507 df-oadd 8510 df-er 8745 df-en 8986 df-dom 8987 df-sdom 8988 df-fin 8989 df-dju 9941 df-card 9979 df-pnf 11297 df-mnf 11298 df-xr 11299 df-ltxr 11300 df-le 11301 df-sub 11494 df-neg 11495 df-nn 12267 df-2 12329 df-n0 12527 df-xnn0 12600 df-z 12614 df-uz 12879 df-xadd 13155 df-fz 13548 df-hash 14370 df-edg 29065 df-uhgr 29075 df-ushgr 29076 df-upgr 29099 df-umgr 29100 df-uspgr 29167 df-usgr 29168 df-nbgr 29350 df-vtxdg 29484 df-frgr 30278 |
| This theorem is referenced by: frgrwopreg1 30337 |
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