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Mirrors > Home > MPE Home > Th. List > frrusgrord0 | Structured version Visualization version GIF version |
Description: If a nonempty finite friendship graph is k-regular, its order is k(k-1)+1. This corresponds to claim 3 in [Huneke] p. 2: "Next we claim that the number n of vertices in G is exactly k(k-1)+1.". (Contributed by Alexander van der Vekens, 11-Mar-2018.) (Revised by AV, 26-May-2021.) (Proof shortened by AV, 12-Jan-2022.) |
Ref | Expression |
---|---|
frrusgrord0.v | ⊢ 𝑉 = (Vtx‘𝐺) |
Ref | Expression |
---|---|
frrusgrord0 | ⊢ ((𝐺 ∈ FriendGraph ∧ 𝑉 ∈ Fin ∧ 𝑉 ≠ ∅) → (∀𝑣 ∈ 𝑉 ((VtxDeg‘𝐺)‘𝑣) = 𝐾 → (♯‘𝑉) = ((𝐾 · (𝐾 − 1)) + 1))) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | frgrusgr 28024 | . . . . . . 7 ⊢ (𝐺 ∈ FriendGraph → 𝐺 ∈ USGraph) | |
2 | 1 | anim1i 616 | . . . . . 6 ⊢ ((𝐺 ∈ FriendGraph ∧ 𝑉 ∈ Fin) → (𝐺 ∈ USGraph ∧ 𝑉 ∈ Fin)) |
3 | frrusgrord0.v | . . . . . . 7 ⊢ 𝑉 = (Vtx‘𝐺) | |
4 | 3 | isfusgr 27086 | . . . . . 6 ⊢ (𝐺 ∈ FinUSGraph ↔ (𝐺 ∈ USGraph ∧ 𝑉 ∈ Fin)) |
5 | 2, 4 | sylibr 236 | . . . . 5 ⊢ ((𝐺 ∈ FriendGraph ∧ 𝑉 ∈ Fin) → 𝐺 ∈ FinUSGraph) |
6 | 3 | fusgreghash2wsp 28101 | . . . . 5 ⊢ ((𝐺 ∈ FinUSGraph ∧ 𝑉 ≠ ∅) → (∀𝑣 ∈ 𝑉 ((VtxDeg‘𝐺)‘𝑣) = 𝐾 → (♯‘(2 WSPathsN 𝐺)) = ((♯‘𝑉) · (𝐾 · (𝐾 − 1))))) |
7 | 5, 6 | stoic3 1777 | . . . 4 ⊢ ((𝐺 ∈ FriendGraph ∧ 𝑉 ∈ Fin ∧ 𝑉 ≠ ∅) → (∀𝑣 ∈ 𝑉 ((VtxDeg‘𝐺)‘𝑣) = 𝐾 → (♯‘(2 WSPathsN 𝐺)) = ((♯‘𝑉) · (𝐾 · (𝐾 − 1))))) |
8 | 7 | imp 409 | . . 3 ⊢ (((𝐺 ∈ FriendGraph ∧ 𝑉 ∈ Fin ∧ 𝑉 ≠ ∅) ∧ ∀𝑣 ∈ 𝑉 ((VtxDeg‘𝐺)‘𝑣) = 𝐾) → (♯‘(2 WSPathsN 𝐺)) = ((♯‘𝑉) · (𝐾 · (𝐾 − 1)))) |
9 | 3 | frgrhash2wsp 28095 | . . . . . . . 8 ⊢ ((𝐺 ∈ FriendGraph ∧ 𝑉 ∈ Fin) → (♯‘(2 WSPathsN 𝐺)) = ((♯‘𝑉) · ((♯‘𝑉) − 1))) |
10 | 9 | eqcomd 2827 | . . . . . . 7 ⊢ ((𝐺 ∈ FriendGraph ∧ 𝑉 ∈ Fin) → ((♯‘𝑉) · ((♯‘𝑉) − 1)) = (♯‘(2 WSPathsN 𝐺))) |
11 | 10 | eqeq1d 2823 | . . . . . 6 ⊢ ((𝐺 ∈ FriendGraph ∧ 𝑉 ∈ Fin) → (((♯‘𝑉) · ((♯‘𝑉) − 1)) = ((♯‘𝑉) · (𝐾 · (𝐾 − 1))) ↔ (♯‘(2 WSPathsN 𝐺)) = ((♯‘𝑉) · (𝐾 · (𝐾 − 1))))) |
12 | 11 | 3adant3 1128 | . . . . 5 ⊢ ((𝐺 ∈ FriendGraph ∧ 𝑉 ∈ Fin ∧ 𝑉 ≠ ∅) → (((♯‘𝑉) · ((♯‘𝑉) − 1)) = ((♯‘𝑉) · (𝐾 · (𝐾 − 1))) ↔ (♯‘(2 WSPathsN 𝐺)) = ((♯‘𝑉) · (𝐾 · (𝐾 − 1))))) |
13 | 12 | adantr 483 | . . . 4 ⊢ (((𝐺 ∈ FriendGraph ∧ 𝑉 ∈ Fin ∧ 𝑉 ≠ ∅) ∧ ∀𝑣 ∈ 𝑉 ((VtxDeg‘𝐺)‘𝑣) = 𝐾) → (((♯‘𝑉) · ((♯‘𝑉) − 1)) = ((♯‘𝑉) · (𝐾 · (𝐾 − 1))) ↔ (♯‘(2 WSPathsN 𝐺)) = ((♯‘𝑉) · (𝐾 · (𝐾 − 1))))) |
14 | 3 | frrusgrord0lem 28102 | . . . . 5 ⊢ (((𝐺 ∈ FriendGraph ∧ 𝑉 ∈ Fin ∧ 𝑉 ≠ ∅) ∧ ∀𝑣 ∈ 𝑉 ((VtxDeg‘𝐺)‘𝑣) = 𝐾) → (𝐾 ∈ ℂ ∧ (♯‘𝑉) ∈ ℂ ∧ (♯‘𝑉) ≠ 0)) |
15 | peano2cnm 10938 | . . . . . . . 8 ⊢ ((♯‘𝑉) ∈ ℂ → ((♯‘𝑉) − 1) ∈ ℂ) | |
16 | 15 | 3ad2ant2 1130 | . . . . . . 7 ⊢ ((𝐾 ∈ ℂ ∧ (♯‘𝑉) ∈ ℂ ∧ (♯‘𝑉) ≠ 0) → ((♯‘𝑉) − 1) ∈ ℂ) |
17 | kcnktkm1cn 11057 | . . . . . . . 8 ⊢ (𝐾 ∈ ℂ → (𝐾 · (𝐾 − 1)) ∈ ℂ) | |
18 | 17 | 3ad2ant1 1129 | . . . . . . 7 ⊢ ((𝐾 ∈ ℂ ∧ (♯‘𝑉) ∈ ℂ ∧ (♯‘𝑉) ≠ 0) → (𝐾 · (𝐾 − 1)) ∈ ℂ) |
19 | simp2 1133 | . . . . . . 7 ⊢ ((𝐾 ∈ ℂ ∧ (♯‘𝑉) ∈ ℂ ∧ (♯‘𝑉) ≠ 0) → (♯‘𝑉) ∈ ℂ) | |
20 | simp3 1134 | . . . . . . 7 ⊢ ((𝐾 ∈ ℂ ∧ (♯‘𝑉) ∈ ℂ ∧ (♯‘𝑉) ≠ 0) → (♯‘𝑉) ≠ 0) | |
21 | 16, 18, 19, 20 | mulcand 11259 | . . . . . 6 ⊢ ((𝐾 ∈ ℂ ∧ (♯‘𝑉) ∈ ℂ ∧ (♯‘𝑉) ≠ 0) → (((♯‘𝑉) · ((♯‘𝑉) − 1)) = ((♯‘𝑉) · (𝐾 · (𝐾 − 1))) ↔ ((♯‘𝑉) − 1) = (𝐾 · (𝐾 − 1)))) |
22 | npcan1 11051 | . . . . . . . . 9 ⊢ ((♯‘𝑉) ∈ ℂ → (((♯‘𝑉) − 1) + 1) = (♯‘𝑉)) | |
23 | oveq1 7149 | . . . . . . . . 9 ⊢ (((♯‘𝑉) − 1) = (𝐾 · (𝐾 − 1)) → (((♯‘𝑉) − 1) + 1) = ((𝐾 · (𝐾 − 1)) + 1)) | |
24 | 22, 23 | sylan9req 2877 | . . . . . . . 8 ⊢ (((♯‘𝑉) ∈ ℂ ∧ ((♯‘𝑉) − 1) = (𝐾 · (𝐾 − 1))) → (♯‘𝑉) = ((𝐾 · (𝐾 − 1)) + 1)) |
25 | 24 | ex 415 | . . . . . . 7 ⊢ ((♯‘𝑉) ∈ ℂ → (((♯‘𝑉) − 1) = (𝐾 · (𝐾 − 1)) → (♯‘𝑉) = ((𝐾 · (𝐾 − 1)) + 1))) |
26 | 25 | 3ad2ant2 1130 | . . . . . 6 ⊢ ((𝐾 ∈ ℂ ∧ (♯‘𝑉) ∈ ℂ ∧ (♯‘𝑉) ≠ 0) → (((♯‘𝑉) − 1) = (𝐾 · (𝐾 − 1)) → (♯‘𝑉) = ((𝐾 · (𝐾 − 1)) + 1))) |
27 | 21, 26 | sylbid 242 | . . . . 5 ⊢ ((𝐾 ∈ ℂ ∧ (♯‘𝑉) ∈ ℂ ∧ (♯‘𝑉) ≠ 0) → (((♯‘𝑉) · ((♯‘𝑉) − 1)) = ((♯‘𝑉) · (𝐾 · (𝐾 − 1))) → (♯‘𝑉) = ((𝐾 · (𝐾 − 1)) + 1))) |
28 | 14, 27 | syl 17 | . . . 4 ⊢ (((𝐺 ∈ FriendGraph ∧ 𝑉 ∈ Fin ∧ 𝑉 ≠ ∅) ∧ ∀𝑣 ∈ 𝑉 ((VtxDeg‘𝐺)‘𝑣) = 𝐾) → (((♯‘𝑉) · ((♯‘𝑉) − 1)) = ((♯‘𝑉) · (𝐾 · (𝐾 − 1))) → (♯‘𝑉) = ((𝐾 · (𝐾 − 1)) + 1))) |
29 | 13, 28 | sylbird 262 | . . 3 ⊢ (((𝐺 ∈ FriendGraph ∧ 𝑉 ∈ Fin ∧ 𝑉 ≠ ∅) ∧ ∀𝑣 ∈ 𝑉 ((VtxDeg‘𝐺)‘𝑣) = 𝐾) → ((♯‘(2 WSPathsN 𝐺)) = ((♯‘𝑉) · (𝐾 · (𝐾 − 1))) → (♯‘𝑉) = ((𝐾 · (𝐾 − 1)) + 1))) |
30 | 8, 29 | mpd 15 | . 2 ⊢ (((𝐺 ∈ FriendGraph ∧ 𝑉 ∈ Fin ∧ 𝑉 ≠ ∅) ∧ ∀𝑣 ∈ 𝑉 ((VtxDeg‘𝐺)‘𝑣) = 𝐾) → (♯‘𝑉) = ((𝐾 · (𝐾 − 1)) + 1)) |
31 | 30 | ex 415 | 1 ⊢ ((𝐺 ∈ FriendGraph ∧ 𝑉 ∈ Fin ∧ 𝑉 ≠ ∅) → (∀𝑣 ∈ 𝑉 ((VtxDeg‘𝐺)‘𝑣) = 𝐾 → (♯‘𝑉) = ((𝐾 · (𝐾 − 1)) + 1))) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ↔ wb 208 ∧ wa 398 ∧ w3a 1083 = wceq 1537 ∈ wcel 2114 ≠ wne 3016 ∀wral 3138 ∅c0 4279 ‘cfv 6341 (class class class)co 7142 Fincfn 8495 ℂcc 10521 0cc0 10523 1c1 10524 + caddc 10526 · cmul 10528 − cmin 10856 2c2 11679 ♯chash 13680 Vtxcvtx 26767 USGraphcusgr 26920 FinUSGraphcfusgr 27084 VtxDegcvtxdg 27233 WSPathsN cwwspthsn 27592 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-inf2 9090 ax-ac2 9871 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 ax-pre-sup 10601 |
This theorem depends on definitions: df-bi 209 df-an 399 df-or 844 df-ifp 1058 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-disj 5018 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-se 5501 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-isom 6350 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-map 8394 df-pm 8395 df-en 8496 df-dom 8497 df-sdom 8498 df-fin 8499 df-sup 8892 df-oi 8960 df-dju 9316 df-card 9354 df-ac 9528 df-pnf 10663 df-mnf 10664 df-xr 10665 df-ltxr 10666 df-le 10667 df-sub 10858 df-neg 10859 df-div 11284 df-nn 11625 df-2 11687 df-3 11688 df-n0 11885 df-xnn0 11955 df-z 11969 df-uz 12231 df-rp 12377 df-xadd 12495 df-fz 12883 df-fzo 13024 df-seq 13360 df-exp 13420 df-hash 13681 df-word 13852 df-concat 13908 df-s1 13935 df-s2 14195 df-s3 14196 df-cj 14443 df-re 14444 df-im 14445 df-sqrt 14579 df-abs 14580 df-clim 14830 df-sum 15028 df-vtx 26769 df-iedg 26770 df-edg 26819 df-uhgr 26829 df-ushgr 26830 df-upgr 26853 df-umgr 26854 df-uspgr 26921 df-usgr 26922 df-fusgr 27085 df-nbgr 27101 df-vtxdg 27234 df-wlks 27367 df-wlkson 27368 df-trls 27460 df-trlson 27461 df-pths 27483 df-spths 27484 df-pthson 27485 df-spthson 27486 df-wwlks 27594 df-wwlksn 27595 df-wwlksnon 27596 df-wspthsn 27597 df-wspthsnon 27598 df-frgr 28022 |
This theorem is referenced by: frrusgrord 28104 |
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