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Theorem numclwwlkovf2num 26612
 Description: In a k regular graph, therere are k closed walks of length 2 starting at a fixed vertex. (Contributed by Alexander van der Vekens, 19-Sep-2018.)
Hypotheses
Ref Expression
numclwwlk.c 𝐶 = (𝑛 ∈ ℕ0 ↦ ((𝑉 ClWWalksN 𝐸)‘𝑛))
numclwwlk.f 𝐹 = (𝑣𝑉, 𝑛 ∈ ℕ0 ↦ {𝑤 ∈ (𝐶𝑛) ∣ (𝑤‘0) = 𝑣})
Assertion
Ref Expression
numclwwlkovf2num ((⟨𝑉, 𝐸⟩ RegUSGrph 𝐾𝑋𝑉) → (#‘(𝑋𝐹2)) = 𝐾)
Distinct variable groups:   𝑛,𝐸   𝑛,𝑉   𝑤,𝐶,𝑛,𝑣   𝑛,𝑋,𝑣,𝑤   𝑣,𝑉   𝑤,𝐸   𝑤,𝑉
Allowed substitution hints:   𝐸(𝑣)   𝐹(𝑤,𝑣,𝑛)   𝐾(𝑤,𝑣,𝑛)

Proof of Theorem numclwwlkovf2num
StepHypRef Expression
1 rusisusgra 26458 . . . 4 (⟨𝑉, 𝐸⟩ RegUSGrph 𝐾𝑉 USGrph 𝐸)
2 numclwwlk.c . . . . 5 𝐶 = (𝑛 ∈ ℕ0 ↦ ((𝑉 ClWWalksN 𝐸)‘𝑛))
3 numclwwlk.f . . . . 5 𝐹 = (𝑣𝑉, 𝑛 ∈ ℕ0 ↦ {𝑤 ∈ (𝐶𝑛) ∣ (𝑤‘0) = 𝑣})
42, 3numclwwlkovf2 26611 . . . 4 ((𝑉 USGrph 𝐸𝑋𝑉) → (𝑋𝐹2) = {𝑤 ∈ Word 𝑉 ∣ ((#‘𝑤) = 2 ∧ {(𝑤‘0), (𝑤‘1)} ∈ ran 𝐸 ∧ (𝑤‘0) = 𝑋)})
51, 4sylan 487 . . 3 ((⟨𝑉, 𝐸⟩ RegUSGrph 𝐾𝑋𝑉) → (𝑋𝐹2) = {𝑤 ∈ Word 𝑉 ∣ ((#‘𝑤) = 2 ∧ {(𝑤‘0), (𝑤‘1)} ∈ ran 𝐸 ∧ (𝑤‘0) = 𝑋)})
65fveq2d 6107 . 2 ((⟨𝑉, 𝐸⟩ RegUSGrph 𝐾𝑋𝑉) → (#‘(𝑋𝐹2)) = (#‘{𝑤 ∈ Word 𝑉 ∣ ((#‘𝑤) = 2 ∧ {(𝑤‘0), (𝑤‘1)} ∈ ran 𝐸 ∧ (𝑤‘0) = 𝑋)}))
7 3ancomb 1040 . . . . . 6 (((#‘𝑤) = 2 ∧ (𝑤‘0) = 𝑋 ∧ {(𝑤‘0), (𝑤‘1)} ∈ ran 𝐸) ↔ ((#‘𝑤) = 2 ∧ {(𝑤‘0), (𝑤‘1)} ∈ ran 𝐸 ∧ (𝑤‘0) = 𝑋))
87a1i 11 . . . . 5 (𝑤 ∈ Word 𝑉 → (((#‘𝑤) = 2 ∧ (𝑤‘0) = 𝑋 ∧ {(𝑤‘0), (𝑤‘1)} ∈ ran 𝐸) ↔ ((#‘𝑤) = 2 ∧ {(𝑤‘0), (𝑤‘1)} ∈ ran 𝐸 ∧ (𝑤‘0) = 𝑋)))
98rabbiia 3161 . . . 4 {𝑤 ∈ Word 𝑉 ∣ ((#‘𝑤) = 2 ∧ (𝑤‘0) = 𝑋 ∧ {(𝑤‘0), (𝑤‘1)} ∈ ran 𝐸)} = {𝑤 ∈ Word 𝑉 ∣ ((#‘𝑤) = 2 ∧ {(𝑤‘0), (𝑤‘1)} ∈ ran 𝐸 ∧ (𝑤‘0) = 𝑋)}
109fveq2i 6106 . . 3 (#‘{𝑤 ∈ Word 𝑉 ∣ ((#‘𝑤) = 2 ∧ (𝑤‘0) = 𝑋 ∧ {(𝑤‘0), (𝑤‘1)} ∈ ran 𝐸)}) = (#‘{𝑤 ∈ Word 𝑉 ∣ ((#‘𝑤) = 2 ∧ {(𝑤‘0), (𝑤‘1)} ∈ ran 𝐸 ∧ (𝑤‘0) = 𝑋)})
11 rusgranumwwlkl1 26473 . . 3 ((⟨𝑉, 𝐸⟩ RegUSGrph 𝐾𝑋𝑉) → (#‘{𝑤 ∈ Word 𝑉 ∣ ((#‘𝑤) = 2 ∧ (𝑤‘0) = 𝑋 ∧ {(𝑤‘0), (𝑤‘1)} ∈ ran 𝐸)}) = 𝐾)
1210, 11syl5eqr 2658 . 2 ((⟨𝑉, 𝐸⟩ RegUSGrph 𝐾𝑋𝑉) → (#‘{𝑤 ∈ Word 𝑉 ∣ ((#‘𝑤) = 2 ∧ {(𝑤‘0), (𝑤‘1)} ∈ ran 𝐸 ∧ (𝑤‘0) = 𝑋)}) = 𝐾)
136, 12eqtrd 2644 1 ((⟨𝑉, 𝐸⟩ RegUSGrph 𝐾𝑋𝑉) → (#‘(𝑋𝐹2)) = 𝐾)
 Colors of variables: wff setvar class Syntax hints:   → wi 4   ↔ wb 195   ∧ wa 383   ∧ w3a 1031   = wceq 1475   ∈ wcel 1977  {crab 2900  {cpr 4127  ⟨cop 4131   class class class wbr 4583   ↦ cmpt 4643  ran crn 5039  ‘cfv 5804  (class class class)co 6549   ↦ cmpt2 6551  0cc0 9815  1c1 9816  2c2 10947  ℕ0cn0 11169  #chash 12979  Word cword 13146   USGrph cusg 25859   ClWWalksN cclwwlkn 26277   RegUSGrph crusgra 26450 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-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 This theorem depends on definitions:  df-bi 196  df-or 384  df-an 385  df-3or 1032  df-3an 1033  df-tru 1478  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-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-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-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-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-nn 10898  df-2 10956  df-n0 11170  df-xnn0 11241  df-z 11255  df-uz 11564  df-xadd 11823  df-fz 12198  df-fzo 12335  df-hash 12980  df-word 13154  df-lsw 13155  df-usgra 25862  df-nbgra 25949  df-clwwlk 26279  df-clwwlkn 26280  df-vdgr 26421  df-rgra 26451  df-rusgra 26452 This theorem is referenced by:  numclwwlk5lem  26638
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