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Mirrors > Home > MPE Home > Th. List > Mathboxes > rusgrnumwlkg | Structured version Visualization version GIF version |
Description: In a k-regular graph, the number of walks of a fixed length n from a fixed vertex is k to the power of n. This theorem corresponds to statement 11 in [Huneke] p. 2: "The total number of walks v(0) v(1) ... v(n-2) from a fixed vertex v = v(0) is k^(n-2) as G is k-regular.". This theorem even holds for n=0: then the walk consists of only one vertex v(0), so the number of walks of length n=0 starting with v=v(0) is 1=k^0. (Contributed by Alexander van der Vekens, 24-Aug-2018.) (Revised by AV, 7-May-2021.) |
Ref | Expression |
---|---|
rusgrnumwwlkg.v | ⊢ 𝑉 = (Vtx‘𝐺) |
Ref | Expression |
---|---|
rusgrnumwlkg | ⊢ ((𝐺 RegUSGraph 𝐾 ∧ (𝑉 ∈ Fin ∧ 𝑃 ∈ 𝑉 ∧ 𝑁 ∈ ℕ0)) → (#‘{𝑤 ∈ (1Walks‘𝐺) ∣ ((#‘(1st ‘𝑤)) = 𝑁 ∧ ((2nd ‘𝑤)‘0) = 𝑃)}) = (𝐾↑𝑁)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | ovex 6577 | . . . 4 ⊢ (𝑁 WWalkSN 𝐺) ∈ V | |
2 | 1 | rabex 4740 | . . 3 ⊢ {𝑝 ∈ (𝑁 WWalkSN 𝐺) ∣ (𝑝‘0) = 𝑃} ∈ V |
3 | rusgrusgr 40764 | . . . . . 6 ⊢ (𝐺 RegUSGraph 𝐾 → 𝐺 ∈ USGraph ) | |
4 | 3 | adantr 480 | . . . . 5 ⊢ ((𝐺 RegUSGraph 𝐾 ∧ (𝑉 ∈ Fin ∧ 𝑃 ∈ 𝑉 ∧ 𝑁 ∈ ℕ0)) → 𝐺 ∈ USGraph ) |
5 | simpr3 1062 | . . . . 5 ⊢ ((𝐺 RegUSGraph 𝐾 ∧ (𝑉 ∈ Fin ∧ 𝑃 ∈ 𝑉 ∧ 𝑁 ∈ ℕ0)) → 𝑁 ∈ ℕ0) | |
6 | rusgrnumwwlkg.v | . . . . . . . . 9 ⊢ 𝑉 = (Vtx‘𝐺) | |
7 | 6 | eleq2i 2680 | . . . . . . . 8 ⊢ (𝑃 ∈ 𝑉 ↔ 𝑃 ∈ (Vtx‘𝐺)) |
8 | 7 | biimpi 205 | . . . . . . 7 ⊢ (𝑃 ∈ 𝑉 → 𝑃 ∈ (Vtx‘𝐺)) |
9 | 8 | 3ad2ant2 1076 | . . . . . 6 ⊢ ((𝑉 ∈ Fin ∧ 𝑃 ∈ 𝑉 ∧ 𝑁 ∈ ℕ0) → 𝑃 ∈ (Vtx‘𝐺)) |
10 | 9 | adantl 481 | . . . . 5 ⊢ ((𝐺 RegUSGraph 𝐾 ∧ (𝑉 ∈ Fin ∧ 𝑃 ∈ 𝑉 ∧ 𝑁 ∈ ℕ0)) → 𝑃 ∈ (Vtx‘𝐺)) |
11 | wlksnwwlknvbij 41114 | . . . . 5 ⊢ ((𝐺 ∈ USGraph ∧ 𝑁 ∈ ℕ0 ∧ 𝑃 ∈ (Vtx‘𝐺)) → ∃𝑓 𝑓:{𝑤 ∈ (1Walks‘𝐺) ∣ ((#‘(1st ‘𝑤)) = 𝑁 ∧ ((2nd ‘𝑤)‘0) = 𝑃)}–1-1-onto→{𝑝 ∈ (𝑁 WWalkSN 𝐺) ∣ (𝑝‘0) = 𝑃}) | |
12 | 4, 5, 10, 11 | syl3anc 1318 | . . . 4 ⊢ ((𝐺 RegUSGraph 𝐾 ∧ (𝑉 ∈ Fin ∧ 𝑃 ∈ 𝑉 ∧ 𝑁 ∈ ℕ0)) → ∃𝑓 𝑓:{𝑤 ∈ (1Walks‘𝐺) ∣ ((#‘(1st ‘𝑤)) = 𝑁 ∧ ((2nd ‘𝑤)‘0) = 𝑃)}–1-1-onto→{𝑝 ∈ (𝑁 WWalkSN 𝐺) ∣ (𝑝‘0) = 𝑃}) |
13 | f1oexbi 7009 | . . . 4 ⊢ (∃𝑔 𝑔:{𝑝 ∈ (𝑁 WWalkSN 𝐺) ∣ (𝑝‘0) = 𝑃}–1-1-onto→{𝑤 ∈ (1Walks‘𝐺) ∣ ((#‘(1st ‘𝑤)) = 𝑁 ∧ ((2nd ‘𝑤)‘0) = 𝑃)} ↔ ∃𝑓 𝑓:{𝑤 ∈ (1Walks‘𝐺) ∣ ((#‘(1st ‘𝑤)) = 𝑁 ∧ ((2nd ‘𝑤)‘0) = 𝑃)}–1-1-onto→{𝑝 ∈ (𝑁 WWalkSN 𝐺) ∣ (𝑝‘0) = 𝑃}) | |
14 | 12, 13 | sylibr 223 | . . 3 ⊢ ((𝐺 RegUSGraph 𝐾 ∧ (𝑉 ∈ Fin ∧ 𝑃 ∈ 𝑉 ∧ 𝑁 ∈ ℕ0)) → ∃𝑔 𝑔:{𝑝 ∈ (𝑁 WWalkSN 𝐺) ∣ (𝑝‘0) = 𝑃}–1-1-onto→{𝑤 ∈ (1Walks‘𝐺) ∣ ((#‘(1st ‘𝑤)) = 𝑁 ∧ ((2nd ‘𝑤)‘0) = 𝑃)}) |
15 | hasheqf1oi 13002 | . . 3 ⊢ ({𝑝 ∈ (𝑁 WWalkSN 𝐺) ∣ (𝑝‘0) = 𝑃} ∈ V → (∃𝑔 𝑔:{𝑝 ∈ (𝑁 WWalkSN 𝐺) ∣ (𝑝‘0) = 𝑃}–1-1-onto→{𝑤 ∈ (1Walks‘𝐺) ∣ ((#‘(1st ‘𝑤)) = 𝑁 ∧ ((2nd ‘𝑤)‘0) = 𝑃)} → (#‘{𝑝 ∈ (𝑁 WWalkSN 𝐺) ∣ (𝑝‘0) = 𝑃}) = (#‘{𝑤 ∈ (1Walks‘𝐺) ∣ ((#‘(1st ‘𝑤)) = 𝑁 ∧ ((2nd ‘𝑤)‘0) = 𝑃)}))) | |
16 | 2, 14, 15 | mpsyl 66 | . 2 ⊢ ((𝐺 RegUSGraph 𝐾 ∧ (𝑉 ∈ Fin ∧ 𝑃 ∈ 𝑉 ∧ 𝑁 ∈ ℕ0)) → (#‘{𝑝 ∈ (𝑁 WWalkSN 𝐺) ∣ (𝑝‘0) = 𝑃}) = (#‘{𝑤 ∈ (1Walks‘𝐺) ∣ ((#‘(1st ‘𝑤)) = 𝑁 ∧ ((2nd ‘𝑤)‘0) = 𝑃)})) |
17 | 6 | rusgrnumwwlkg 41179 | . 2 ⊢ ((𝐺 RegUSGraph 𝐾 ∧ (𝑉 ∈ Fin ∧ 𝑃 ∈ 𝑉 ∧ 𝑁 ∈ ℕ0)) → (#‘{𝑝 ∈ (𝑁 WWalkSN 𝐺) ∣ (𝑝‘0) = 𝑃}) = (𝐾↑𝑁)) |
18 | 16, 17 | eqtr3d 2646 | 1 ⊢ ((𝐺 RegUSGraph 𝐾 ∧ (𝑉 ∈ Fin ∧ 𝑃 ∈ 𝑉 ∧ 𝑁 ∈ ℕ0)) → (#‘{𝑤 ∈ (1Walks‘𝐺) ∣ ((#‘(1st ‘𝑤)) = 𝑁 ∧ ((2nd ‘𝑤)‘0) = 𝑃)}) = (𝐾↑𝑁)) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ∧ wa 383 ∧ w3a 1031 = wceq 1475 ∃wex 1695 ∈ wcel 1977 {crab 2900 Vcvv 3173 class class class wbr 4583 –1-1-onto→wf1o 5803 ‘cfv 5804 (class class class)co 6549 1st c1st 7057 2nd c2nd 7058 Fincfn 7841 0cc0 9815 ℕ0cn0 11169 ↑cexp 12722 #chash 12979 Vtxcvtx 25673 USGraph cusgr 40379 RegUSGraph crusgr 40756 1Walksc1wlks 40796 WWalkSN cwwlksn 41029 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1713 ax-4 1728 ax-5 1827 ax-6 1875 ax-7 1922 ax-8 1979 ax-9 1986 ax-10 2006 ax-11 2021 ax-12 2034 ax-13 2234 ax-ext 2590 ax-rep 4699 ax-sep 4709 ax-nul 4717 ax-pow 4769 ax-pr 4833 ax-un 6847 ax-inf2 8421 ax-cnex 9871 ax-resscn 9872 ax-1cn 9873 ax-icn 9874 ax-addcl 9875 ax-addrcl 9876 ax-mulcl 9877 ax-mulrcl 9878 ax-mulcom 9879 ax-addass 9880 ax-mulass 9881 ax-distr 9882 ax-i2m1 9883 ax-1ne0 9884 ax-1rid 9885 ax-rnegex 9886 ax-rrecex 9887 ax-cnre 9888 ax-pre-lttri 9889 ax-pre-lttrn 9890 ax-pre-ltadd 9891 ax-pre-mulgt0 9892 ax-pre-sup 9893 |
This theorem depends on definitions: df-bi 196 df-or 384 df-an 385 df-ifp 1007 df-3or 1032 df-3an 1033 df-tru 1478 df-fal 1481 df-ex 1696 df-nf 1701 df-sb 1868 df-eu 2462 df-mo 2463 df-clab 2597 df-cleq 2603 df-clel 2606 df-nfc 2740 df-ne 2782 df-nel 2783 df-ral 2901 df-rex 2902 df-reu 2903 df-rmo 2904 df-rab 2905 df-v 3175 df-sbc 3403 df-csb 3500 df-dif 3543 df-un 3545 df-in 3547 df-ss 3554 df-pss 3556 df-nul 3875 df-if 4037 df-pw 4110 df-sn 4126 df-pr 4128 df-tp 4130 df-op 4132 df-uni 4373 df-int 4411 df-iun 4457 df-disj 4554 df-br 4584 df-opab 4644 df-mpt 4645 df-tr 4681 df-eprel 4949 df-id 4953 df-po 4959 df-so 4960 df-fr 4997 df-se 4998 df-we 4999 df-xp 5044 df-rel 5045 df-cnv 5046 df-co 5047 df-dm 5048 df-rn 5049 df-res 5050 df-ima 5051 df-pred 5597 df-ord 5643 df-on 5644 df-lim 5645 df-suc 5646 df-iota 5768 df-fun 5806 df-fn 5807 df-f 5808 df-f1 5809 df-fo 5810 df-f1o 5811 df-fv 5812 df-isom 5813 df-riota 6511 df-ov 6552 df-oprab 6553 df-mpt2 6554 df-om 6958 df-1st 7059 df-2nd 7060 df-wrecs 7294 df-recs 7355 df-rdg 7393 df-1o 7447 df-2o 7448 df-oadd 7451 df-er 7629 df-map 7746 df-pm 7747 df-en 7842 df-dom 7843 df-sdom 7844 df-fin 7845 df-sup 8231 df-oi 8298 df-card 8648 df-cda 8873 df-pnf 9955 df-mnf 9956 df-xr 9957 df-ltxr 9958 df-le 9959 df-sub 10147 df-neg 10148 df-div 10564 df-nn 10898 df-2 10956 df-3 10957 df-n0 11170 df-xnn0 11241 df-z 11255 df-uz 11564 df-rp 11709 df-xadd 11823 df-fz 12198 df-fzo 12335 df-seq 12664 df-exp 12723 df-hash 12980 df-word 13154 df-lsw 13155 df-concat 13156 df-s1 13157 df-substr 13158 df-cj 13687 df-re 13688 df-im 13689 df-sqrt 13823 df-abs 13824 df-clim 14067 df-sum 14265 df-vtx 25675 df-iedg 25676 df-uhgr 25724 df-ushgr 25725 df-upgr 25749 df-umgr 25750 df-edga 25793 df-uspgr 40380 df-usgr 40381 df-fusgr 40536 df-nbgr 40554 df-vtxdg 40682 df-rgr 40757 df-rusgr 40758 df-1wlks 40800 df-wlks 40801 df-wwlks 41033 df-wwlksn 41034 |
This theorem is referenced by: (None) |
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