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Mirrors > Home > MPE Home > Th. List > numclwlk1 | Structured version Visualization version GIF version |
Description: Statement 9 in [Huneke] p. 2: "If n > 1, then the number of closed n-walks v(0) ... v(n-2) v(n-1) v(n) from v = v(0) = v(n) with v(n-2) = v is kf(n-2)". Since πΊ is k-regular, the vertex v(n-2) = v has k neighbors v(n-1), so there are k walks from v(n-2) = v to v(n) = v (via each of v's neighbors) completing each of the f(n-2) walks from v=v(0) to v(n-2)=v. This theorem holds even for k=0. (Contributed by AV, 23-May-2022.) |
Ref | Expression |
---|---|
numclwlk1.v | β’ π = (VtxβπΊ) |
numclwlk1.c | β’ πΆ = {π€ β (ClWalksβπΊ) β£ ((β―β(1st βπ€)) = π β§ ((2nd βπ€)β0) = π β§ ((2nd βπ€)β(π β 2)) = π)} |
numclwlk1.f | β’ πΉ = {π€ β (ClWalksβπΊ) β£ ((β―β(1st βπ€)) = (π β 2) β§ ((2nd βπ€)β0) = π)} |
Ref | Expression |
---|---|
numclwlk1 | β’ (((π β Fin β§ πΊ RegUSGraph πΎ) β§ (π β π β§ π β (β€β₯β2))) β (β―βπΆ) = (πΎ Β· (β―βπΉ))) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | uzp1 12893 | . . . 4 β’ (π β (β€β₯β2) β (π = 2 β¨ π β (β€β₯β(2 + 1)))) | |
2 | numclwlk1.v | . . . . . . . 8 β’ π = (VtxβπΊ) | |
3 | numclwlk1.c | . . . . . . . 8 β’ πΆ = {π€ β (ClWalksβπΊ) β£ ((β―β(1st βπ€)) = π β§ ((2nd βπ€)β0) = π β§ ((2nd βπ€)β(π β 2)) = π)} | |
4 | numclwlk1.f | . . . . . . . 8 β’ πΉ = {π€ β (ClWalksβπΊ) β£ ((β―β(1st βπ€)) = (π β 2) β§ ((2nd βπ€)β0) = π)} | |
5 | 2, 3, 4 | numclwlk1lem1 30223 | . . . . . . 7 β’ (((π β Fin β§ πΊ RegUSGraph πΎ) β§ (π β π β§ π = 2)) β (β―βπΆ) = (πΎ Β· (β―βπΉ))) |
6 | 5 | expcom 412 | . . . . . 6 β’ ((π β π β§ π = 2) β ((π β Fin β§ πΊ RegUSGraph πΎ) β (β―βπΆ) = (πΎ Β· (β―βπΉ)))) |
7 | 6 | expcom 412 | . . . . 5 β’ (π = 2 β (π β π β ((π β Fin β§ πΊ RegUSGraph πΎ) β (β―βπΆ) = (πΎ Β· (β―βπΉ))))) |
8 | 2, 3, 4 | numclwlk1lem2 30224 | . . . . . . . 8 β’ (((π β Fin β§ πΊ RegUSGraph πΎ) β§ (π β π β§ π β (β€β₯β3))) β (β―βπΆ) = (πΎ Β· (β―βπΉ))) |
9 | 8 | expcom 412 | . . . . . . 7 β’ ((π β π β§ π β (β€β₯β3)) β ((π β Fin β§ πΊ RegUSGraph πΎ) β (β―βπΆ) = (πΎ Β· (β―βπΉ)))) |
10 | 9 | expcom 412 | . . . . . 6 β’ (π β (β€β₯β3) β (π β π β ((π β Fin β§ πΊ RegUSGraph πΎ) β (β―βπΆ) = (πΎ Β· (β―βπΉ))))) |
11 | 2p1e3 12384 | . . . . . . 7 β’ (2 + 1) = 3 | |
12 | 11 | fveq2i 6895 | . . . . . 6 β’ (β€β₯β(2 + 1)) = (β€β₯β3) |
13 | 10, 12 | eleq2s 2843 | . . . . 5 β’ (π β (β€β₯β(2 + 1)) β (π β π β ((π β Fin β§ πΊ RegUSGraph πΎ) β (β―βπΆ) = (πΎ Β· (β―βπΉ))))) |
14 | 7, 13 | jaoi 855 | . . . 4 β’ ((π = 2 β¨ π β (β€β₯β(2 + 1))) β (π β π β ((π β Fin β§ πΊ RegUSGraph πΎ) β (β―βπΆ) = (πΎ Β· (β―βπΉ))))) |
15 | 1, 14 | syl 17 | . . 3 β’ (π β (β€β₯β2) β (π β π β ((π β Fin β§ πΊ RegUSGraph πΎ) β (β―βπΆ) = (πΎ Β· (β―βπΉ))))) |
16 | 15 | impcom 406 | . 2 β’ ((π β π β§ π β (β€β₯β2)) β ((π β Fin β§ πΊ RegUSGraph πΎ) β (β―βπΆ) = (πΎ Β· (β―βπΉ)))) |
17 | 16 | impcom 406 | 1 β’ (((π β Fin β§ πΊ RegUSGraph πΎ) β§ (π β π β§ π β (β€β₯β2))) β (β―βπΆ) = (πΎ Β· (β―βπΉ))) |
Colors of variables: wff setvar class |
Syntax hints: β wi 4 β§ wa 394 β¨ wo 845 β§ w3a 1084 = wceq 1533 β wcel 2098 {crab 3419 class class class wbr 5143 βcfv 6543 (class class class)co 7416 1st c1st 7989 2nd c2nd 7990 Fincfn 8962 0cc0 11138 1c1 11139 + caddc 11141 Β· cmul 11143 β cmin 11474 2c2 12297 3c3 12298 β€β₯cuz 12852 β―chash 14321 Vtxcvtx 28853 RegUSGraph crusgr 29414 ClWalkscclwlks 29628 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1789 ax-4 1803 ax-5 1905 ax-6 1963 ax-7 2003 ax-8 2100 ax-9 2108 ax-10 2129 ax-11 2146 ax-12 2166 ax-ext 2696 ax-rep 5280 ax-sep 5294 ax-nul 5301 ax-pow 5359 ax-pr 5423 ax-un 7738 ax-cnex 11194 ax-resscn 11195 ax-1cn 11196 ax-icn 11197 ax-addcl 11198 ax-addrcl 11199 ax-mulcl 11200 ax-mulrcl 11201 ax-mulcom 11202 ax-addass 11203 ax-mulass 11204 ax-distr 11205 ax-i2m1 11206 ax-1ne0 11207 ax-1rid 11208 ax-rnegex 11209 ax-rrecex 11210 ax-cnre 11211 ax-pre-lttri 11212 ax-pre-lttrn 11213 ax-pre-ltadd 11214 ax-pre-mulgt0 11215 |
This theorem depends on definitions: df-bi 206 df-an 395 df-or 846 df-ifp 1061 df-3or 1085 df-3an 1086 df-tru 1536 df-fal 1546 df-ex 1774 df-nf 1778 df-sb 2060 df-mo 2528 df-eu 2557 df-clab 2703 df-cleq 2717 df-clel 2802 df-nfc 2877 df-ne 2931 df-nel 3037 df-ral 3052 df-rex 3061 df-rmo 3364 df-reu 3365 df-rab 3420 df-v 3465 df-sbc 3769 df-csb 3885 df-dif 3942 df-un 3944 df-in 3946 df-ss 3956 df-pss 3959 df-nul 4319 df-if 4525 df-pw 4600 df-sn 4625 df-pr 4627 df-op 4631 df-uni 4904 df-int 4945 df-iun 4993 df-br 5144 df-opab 5206 df-mpt 5227 df-tr 5261 df-id 5570 df-eprel 5576 df-po 5584 df-so 5585 df-fr 5627 df-we 5629 df-xp 5678 df-rel 5679 df-cnv 5680 df-co 5681 df-dm 5682 df-rn 5683 df-res 5684 df-ima 5685 df-pred 6300 df-ord 6367 df-on 6368 df-lim 6369 df-suc 6370 df-iota 6495 df-fun 6545 df-fn 6546 df-f 6547 df-f1 6548 df-fo 6549 df-f1o 6550 df-fv 6551 df-riota 7372 df-ov 7419 df-oprab 7420 df-mpo 7421 df-om 7869 df-1st 7991 df-2nd 7992 df-frecs 8285 df-wrecs 8316 df-recs 8390 df-rdg 8429 df-1o 8485 df-2o 8486 df-oadd 8489 df-er 8723 df-map 8845 df-pm 8846 df-en 8963 df-dom 8964 df-sdom 8965 df-fin 8966 df-dju 9924 df-card 9962 df-pnf 11280 df-mnf 11281 df-xr 11282 df-ltxr 11283 df-le 11284 df-sub 11476 df-neg 11477 df-nn 12243 df-2 12305 df-3 12306 df-n0 12503 df-xnn0 12575 df-z 12589 df-uz 12853 df-rp 13007 df-xadd 13125 df-fz 13517 df-fzo 13660 df-seq 13999 df-exp 14059 df-hash 14322 df-word 14497 df-lsw 14545 df-concat 14553 df-s1 14578 df-substr 14623 df-pfx 14653 df-s2 14831 df-vtx 28855 df-iedg 28856 df-edg 28905 df-uhgr 28915 df-ushgr 28916 df-upgr 28939 df-umgr 28940 df-uspgr 29007 df-usgr 29008 df-fusgr 29174 df-nbgr 29190 df-vtxdg 29324 df-rgr 29415 df-rusgr 29416 df-wlks 29457 df-clwlks 29629 df-wwlks 29685 df-wwlksn 29686 df-clwwlk 29836 df-clwwlkn 29879 df-clwwlknon 29942 |
This theorem is referenced by: (None) |
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