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Theorem lfgrwlkprop 26584
Description: Two adjacent vertices in a walk are different in a loop-free graph. (Contributed by AV, 28-Jan-2021.)
Hypothesis
Ref Expression
lfgrwlkprop.i 𝐼 = (iEdg‘𝐺)
Assertion
Ref Expression
lfgrwlkprop ((𝐹(Walks‘𝐺)𝑃𝐼:dom 𝐼⟶{𝑥 ∈ 𝒫 𝑉 ∣ 2 ≤ (#‘𝑥)}) → ∀𝑘 ∈ (0..^(#‘𝐹))(𝑃𝑘) ≠ (𝑃‘(𝑘 + 1)))
Distinct variable groups:   𝑘,𝐹,𝑥   𝑘,𝐺   𝑘,𝐼,𝑥   𝑃,𝑘   𝑘,𝑉,𝑥
Allowed substitution hints:   𝑃(𝑥)   𝐺(𝑥)

Proof of Theorem lfgrwlkprop
StepHypRef Expression
1 wlkv 26508 . . . . 5 (𝐹(Walks‘𝐺)𝑃 → (𝐺 ∈ V ∧ 𝐹 ∈ V ∧ 𝑃 ∈ V))
2 eqid 2622 . . . . . 6 (Vtx‘𝐺) = (Vtx‘𝐺)
3 lfgrwlkprop.i . . . . . 6 𝐼 = (iEdg‘𝐺)
42, 3iswlk 26506 . . . . 5 ((𝐺 ∈ V ∧ 𝐹 ∈ V ∧ 𝑃 ∈ V) → (𝐹(Walks‘𝐺)𝑃 ↔ (𝐹 ∈ Word dom 𝐼𝑃:(0...(#‘𝐹))⟶(Vtx‘𝐺) ∧ ∀𝑘 ∈ (0..^(#‘𝐹))if-((𝑃𝑘) = (𝑃‘(𝑘 + 1)), (𝐼‘(𝐹𝑘)) = {(𝑃𝑘)}, {(𝑃𝑘), (𝑃‘(𝑘 + 1))} ⊆ (𝐼‘(𝐹𝑘))))))
51, 4syl 17 . . . 4 (𝐹(Walks‘𝐺)𝑃 → (𝐹(Walks‘𝐺)𝑃 ↔ (𝐹 ∈ Word dom 𝐼𝑃:(0...(#‘𝐹))⟶(Vtx‘𝐺) ∧ ∀𝑘 ∈ (0..^(#‘𝐹))if-((𝑃𝑘) = (𝑃‘(𝑘 + 1)), (𝐼‘(𝐹𝑘)) = {(𝑃𝑘)}, {(𝑃𝑘), (𝑃‘(𝑘 + 1))} ⊆ (𝐼‘(𝐹𝑘))))))
6 ifptru 1023 . . . . . . . . . . . 12 ((𝑃𝑘) = (𝑃‘(𝑘 + 1)) → (if-((𝑃𝑘) = (𝑃‘(𝑘 + 1)), (𝐼‘(𝐹𝑘)) = {(𝑃𝑘)}, {(𝑃𝑘), (𝑃‘(𝑘 + 1))} ⊆ (𝐼‘(𝐹𝑘))) ↔ (𝐼‘(𝐹𝑘)) = {(𝑃𝑘)}))
76adantr 481 . . . . . . . . . . 11 (((𝑃𝑘) = (𝑃‘(𝑘 + 1)) ∧ (((𝐹 ∈ Word dom 𝐼𝑃:(0...(#‘𝐹))⟶(Vtx‘𝐺)) ∧ 𝐼:dom 𝐼⟶{𝑥 ∈ 𝒫 𝑉 ∣ 2 ≤ (#‘𝑥)}) ∧ 𝑘 ∈ (0..^(#‘𝐹)))) → (if-((𝑃𝑘) = (𝑃‘(𝑘 + 1)), (𝐼‘(𝐹𝑘)) = {(𝑃𝑘)}, {(𝑃𝑘), (𝑃‘(𝑘 + 1))} ⊆ (𝐼‘(𝐹𝑘))) ↔ (𝐼‘(𝐹𝑘)) = {(𝑃𝑘)}))
8 simplr 792 . . . . . . . . . . . . . 14 ((((𝐹 ∈ Word dom 𝐼𝑃:(0...(#‘𝐹))⟶(Vtx‘𝐺)) ∧ 𝐼:dom 𝐼⟶{𝑥 ∈ 𝒫 𝑉 ∣ 2 ≤ (#‘𝑥)}) ∧ 𝑘 ∈ (0..^(#‘𝐹))) → 𝐼:dom 𝐼⟶{𝑥 ∈ 𝒫 𝑉 ∣ 2 ≤ (#‘𝑥)})
9 wrdsymbcl 13318 . . . . . . . . . . . . . . 15 ((𝐹 ∈ Word dom 𝐼𝑘 ∈ (0..^(#‘𝐹))) → (𝐹𝑘) ∈ dom 𝐼)
109ad4ant14 1293 . . . . . . . . . . . . . 14 ((((𝐹 ∈ Word dom 𝐼𝑃:(0...(#‘𝐹))⟶(Vtx‘𝐺)) ∧ 𝐼:dom 𝐼⟶{𝑥 ∈ 𝒫 𝑉 ∣ 2 ≤ (#‘𝑥)}) ∧ 𝑘 ∈ (0..^(#‘𝐹))) → (𝐹𝑘) ∈ dom 𝐼)
118, 10ffvelrnd 6360 . . . . . . . . . . . . 13 ((((𝐹 ∈ Word dom 𝐼𝑃:(0...(#‘𝐹))⟶(Vtx‘𝐺)) ∧ 𝐼:dom 𝐼⟶{𝑥 ∈ 𝒫 𝑉 ∣ 2 ≤ (#‘𝑥)}) ∧ 𝑘 ∈ (0..^(#‘𝐹))) → (𝐼‘(𝐹𝑘)) ∈ {𝑥 ∈ 𝒫 𝑉 ∣ 2 ≤ (#‘𝑥)})
12 fveq2 6191 . . . . . . . . . . . . . . . 16 (𝑥 = (𝐼‘(𝐹𝑘)) → (#‘𝑥) = (#‘(𝐼‘(𝐹𝑘))))
1312breq2d 4665 . . . . . . . . . . . . . . 15 (𝑥 = (𝐼‘(𝐹𝑘)) → (2 ≤ (#‘𝑥) ↔ 2 ≤ (#‘(𝐼‘(𝐹𝑘)))))
1413elrab 3363 . . . . . . . . . . . . . 14 ((𝐼‘(𝐹𝑘)) ∈ {𝑥 ∈ 𝒫 𝑉 ∣ 2 ≤ (#‘𝑥)} ↔ ((𝐼‘(𝐹𝑘)) ∈ 𝒫 𝑉 ∧ 2 ≤ (#‘(𝐼‘(𝐹𝑘)))))
15 fveq2 6191 . . . . . . . . . . . . . . . . . . 19 ((𝐼‘(𝐹𝑘)) = {(𝑃𝑘)} → (#‘(𝐼‘(𝐹𝑘))) = (#‘{(𝑃𝑘)}))
1615breq2d 4665 . . . . . . . . . . . . . . . . . 18 ((𝐼‘(𝐹𝑘)) = {(𝑃𝑘)} → (2 ≤ (#‘(𝐼‘(𝐹𝑘))) ↔ 2 ≤ (#‘{(𝑃𝑘)})))
17 fvex 6201 . . . . . . . . . . . . . . . . . . . . 21 (𝑃𝑘) ∈ V
18 hashsng 13159 . . . . . . . . . . . . . . . . . . . . 21 ((𝑃𝑘) ∈ V → (#‘{(𝑃𝑘)}) = 1)
1917, 18ax-mp 5 . . . . . . . . . . . . . . . . . . . 20 (#‘{(𝑃𝑘)}) = 1
2019breq2i 4661 . . . . . . . . . . . . . . . . . . 19 (2 ≤ (#‘{(𝑃𝑘)}) ↔ 2 ≤ 1)
21 1lt2 11194 . . . . . . . . . . . . . . . . . . . 20 1 < 2
22 1re 10039 . . . . . . . . . . . . . . . . . . . . . 22 1 ∈ ℝ
23 2re 11090 . . . . . . . . . . . . . . . . . . . . . 22 2 ∈ ℝ
2422, 23ltnlei 10158 . . . . . . . . . . . . . . . . . . . . 21 (1 < 2 ↔ ¬ 2 ≤ 1)
25 pm2.21 120 . . . . . . . . . . . . . . . . . . . . 21 (¬ 2 ≤ 1 → (2 ≤ 1 → (𝑃𝑘) ≠ (𝑃‘(𝑘 + 1))))
2624, 25sylbi 207 . . . . . . . . . . . . . . . . . . . 20 (1 < 2 → (2 ≤ 1 → (𝑃𝑘) ≠ (𝑃‘(𝑘 + 1))))
2721, 26ax-mp 5 . . . . . . . . . . . . . . . . . . 19 (2 ≤ 1 → (𝑃𝑘) ≠ (𝑃‘(𝑘 + 1)))
2820, 27sylbi 207 . . . . . . . . . . . . . . . . . 18 (2 ≤ (#‘{(𝑃𝑘)}) → (𝑃𝑘) ≠ (𝑃‘(𝑘 + 1)))
2916, 28syl6bi 243 . . . . . . . . . . . . . . . . 17 ((𝐼‘(𝐹𝑘)) = {(𝑃𝑘)} → (2 ≤ (#‘(𝐼‘(𝐹𝑘))) → (𝑃𝑘) ≠ (𝑃‘(𝑘 + 1))))
3029com12 32 . . . . . . . . . . . . . . . 16 (2 ≤ (#‘(𝐼‘(𝐹𝑘))) → ((𝐼‘(𝐹𝑘)) = {(𝑃𝑘)} → (𝑃𝑘) ≠ (𝑃‘(𝑘 + 1))))
3130adantl 482 . . . . . . . . . . . . . . 15 (((𝐼‘(𝐹𝑘)) ∈ 𝒫 𝑉 ∧ 2 ≤ (#‘(𝐼‘(𝐹𝑘)))) → ((𝐼‘(𝐹𝑘)) = {(𝑃𝑘)} → (𝑃𝑘) ≠ (𝑃‘(𝑘 + 1))))
3231a1i 11 . . . . . . . . . . . . . 14 ((((𝐹 ∈ Word dom 𝐼𝑃:(0...(#‘𝐹))⟶(Vtx‘𝐺)) ∧ 𝐼:dom 𝐼⟶{𝑥 ∈ 𝒫 𝑉 ∣ 2 ≤ (#‘𝑥)}) ∧ 𝑘 ∈ (0..^(#‘𝐹))) → (((𝐼‘(𝐹𝑘)) ∈ 𝒫 𝑉 ∧ 2 ≤ (#‘(𝐼‘(𝐹𝑘)))) → ((𝐼‘(𝐹𝑘)) = {(𝑃𝑘)} → (𝑃𝑘) ≠ (𝑃‘(𝑘 + 1)))))
3314, 32syl5bi 232 . . . . . . . . . . . . 13 ((((𝐹 ∈ Word dom 𝐼𝑃:(0...(#‘𝐹))⟶(Vtx‘𝐺)) ∧ 𝐼:dom 𝐼⟶{𝑥 ∈ 𝒫 𝑉 ∣ 2 ≤ (#‘𝑥)}) ∧ 𝑘 ∈ (0..^(#‘𝐹))) → ((𝐼‘(𝐹𝑘)) ∈ {𝑥 ∈ 𝒫 𝑉 ∣ 2 ≤ (#‘𝑥)} → ((𝐼‘(𝐹𝑘)) = {(𝑃𝑘)} → (𝑃𝑘) ≠ (𝑃‘(𝑘 + 1)))))
3411, 33mpd 15 . . . . . . . . . . . 12 ((((𝐹 ∈ Word dom 𝐼𝑃:(0...(#‘𝐹))⟶(Vtx‘𝐺)) ∧ 𝐼:dom 𝐼⟶{𝑥 ∈ 𝒫 𝑉 ∣ 2 ≤ (#‘𝑥)}) ∧ 𝑘 ∈ (0..^(#‘𝐹))) → ((𝐼‘(𝐹𝑘)) = {(𝑃𝑘)} → (𝑃𝑘) ≠ (𝑃‘(𝑘 + 1))))
3534adantl 482 . . . . . . . . . . 11 (((𝑃𝑘) = (𝑃‘(𝑘 + 1)) ∧ (((𝐹 ∈ Word dom 𝐼𝑃:(0...(#‘𝐹))⟶(Vtx‘𝐺)) ∧ 𝐼:dom 𝐼⟶{𝑥 ∈ 𝒫 𝑉 ∣ 2 ≤ (#‘𝑥)}) ∧ 𝑘 ∈ (0..^(#‘𝐹)))) → ((𝐼‘(𝐹𝑘)) = {(𝑃𝑘)} → (𝑃𝑘) ≠ (𝑃‘(𝑘 + 1))))
367, 35sylbid 230 . . . . . . . . . 10 (((𝑃𝑘) = (𝑃‘(𝑘 + 1)) ∧ (((𝐹 ∈ Word dom 𝐼𝑃:(0...(#‘𝐹))⟶(Vtx‘𝐺)) ∧ 𝐼:dom 𝐼⟶{𝑥 ∈ 𝒫 𝑉 ∣ 2 ≤ (#‘𝑥)}) ∧ 𝑘 ∈ (0..^(#‘𝐹)))) → (if-((𝑃𝑘) = (𝑃‘(𝑘 + 1)), (𝐼‘(𝐹𝑘)) = {(𝑃𝑘)}, {(𝑃𝑘), (𝑃‘(𝑘 + 1))} ⊆ (𝐼‘(𝐹𝑘))) → (𝑃𝑘) ≠ (𝑃‘(𝑘 + 1))))
3736ex 450 . . . . . . . . 9 ((𝑃𝑘) = (𝑃‘(𝑘 + 1)) → ((((𝐹 ∈ Word dom 𝐼𝑃:(0...(#‘𝐹))⟶(Vtx‘𝐺)) ∧ 𝐼:dom 𝐼⟶{𝑥 ∈ 𝒫 𝑉 ∣ 2 ≤ (#‘𝑥)}) ∧ 𝑘 ∈ (0..^(#‘𝐹))) → (if-((𝑃𝑘) = (𝑃‘(𝑘 + 1)), (𝐼‘(𝐹𝑘)) = {(𝑃𝑘)}, {(𝑃𝑘), (𝑃‘(𝑘 + 1))} ⊆ (𝐼‘(𝐹𝑘))) → (𝑃𝑘) ≠ (𝑃‘(𝑘 + 1)))))
38 neqne 2802 . . . . . . . . . 10 (¬ (𝑃𝑘) = (𝑃‘(𝑘 + 1)) → (𝑃𝑘) ≠ (𝑃‘(𝑘 + 1)))
39382a1d 26 . . . . . . . . 9 (¬ (𝑃𝑘) = (𝑃‘(𝑘 + 1)) → ((((𝐹 ∈ Word dom 𝐼𝑃:(0...(#‘𝐹))⟶(Vtx‘𝐺)) ∧ 𝐼:dom 𝐼⟶{𝑥 ∈ 𝒫 𝑉 ∣ 2 ≤ (#‘𝑥)}) ∧ 𝑘 ∈ (0..^(#‘𝐹))) → (if-((𝑃𝑘) = (𝑃‘(𝑘 + 1)), (𝐼‘(𝐹𝑘)) = {(𝑃𝑘)}, {(𝑃𝑘), (𝑃‘(𝑘 + 1))} ⊆ (𝐼‘(𝐹𝑘))) → (𝑃𝑘) ≠ (𝑃‘(𝑘 + 1)))))
4037, 39pm2.61i 176 . . . . . . . 8 ((((𝐹 ∈ Word dom 𝐼𝑃:(0...(#‘𝐹))⟶(Vtx‘𝐺)) ∧ 𝐼:dom 𝐼⟶{𝑥 ∈ 𝒫 𝑉 ∣ 2 ≤ (#‘𝑥)}) ∧ 𝑘 ∈ (0..^(#‘𝐹))) → (if-((𝑃𝑘) = (𝑃‘(𝑘 + 1)), (𝐼‘(𝐹𝑘)) = {(𝑃𝑘)}, {(𝑃𝑘), (𝑃‘(𝑘 + 1))} ⊆ (𝐼‘(𝐹𝑘))) → (𝑃𝑘) ≠ (𝑃‘(𝑘 + 1))))
4140ralimdva 2962 . . . . . . 7 (((𝐹 ∈ Word dom 𝐼𝑃:(0...(#‘𝐹))⟶(Vtx‘𝐺)) ∧ 𝐼:dom 𝐼⟶{𝑥 ∈ 𝒫 𝑉 ∣ 2 ≤ (#‘𝑥)}) → (∀𝑘 ∈ (0..^(#‘𝐹))if-((𝑃𝑘) = (𝑃‘(𝑘 + 1)), (𝐼‘(𝐹𝑘)) = {(𝑃𝑘)}, {(𝑃𝑘), (𝑃‘(𝑘 + 1))} ⊆ (𝐼‘(𝐹𝑘))) → ∀𝑘 ∈ (0..^(#‘𝐹))(𝑃𝑘) ≠ (𝑃‘(𝑘 + 1))))
4241ex 450 . . . . . 6 ((𝐹 ∈ Word dom 𝐼𝑃:(0...(#‘𝐹))⟶(Vtx‘𝐺)) → (𝐼:dom 𝐼⟶{𝑥 ∈ 𝒫 𝑉 ∣ 2 ≤ (#‘𝑥)} → (∀𝑘 ∈ (0..^(#‘𝐹))if-((𝑃𝑘) = (𝑃‘(𝑘 + 1)), (𝐼‘(𝐹𝑘)) = {(𝑃𝑘)}, {(𝑃𝑘), (𝑃‘(𝑘 + 1))} ⊆ (𝐼‘(𝐹𝑘))) → ∀𝑘 ∈ (0..^(#‘𝐹))(𝑃𝑘) ≠ (𝑃‘(𝑘 + 1)))))
4342com23 86 . . . . 5 ((𝐹 ∈ Word dom 𝐼𝑃:(0...(#‘𝐹))⟶(Vtx‘𝐺)) → (∀𝑘 ∈ (0..^(#‘𝐹))if-((𝑃𝑘) = (𝑃‘(𝑘 + 1)), (𝐼‘(𝐹𝑘)) = {(𝑃𝑘)}, {(𝑃𝑘), (𝑃‘(𝑘 + 1))} ⊆ (𝐼‘(𝐹𝑘))) → (𝐼:dom 𝐼⟶{𝑥 ∈ 𝒫 𝑉 ∣ 2 ≤ (#‘𝑥)} → ∀𝑘 ∈ (0..^(#‘𝐹))(𝑃𝑘) ≠ (𝑃‘(𝑘 + 1)))))
44433impia 1261 . . . 4 ((𝐹 ∈ Word dom 𝐼𝑃:(0...(#‘𝐹))⟶(Vtx‘𝐺) ∧ ∀𝑘 ∈ (0..^(#‘𝐹))if-((𝑃𝑘) = (𝑃‘(𝑘 + 1)), (𝐼‘(𝐹𝑘)) = {(𝑃𝑘)}, {(𝑃𝑘), (𝑃‘(𝑘 + 1))} ⊆ (𝐼‘(𝐹𝑘)))) → (𝐼:dom 𝐼⟶{𝑥 ∈ 𝒫 𝑉 ∣ 2 ≤ (#‘𝑥)} → ∀𝑘 ∈ (0..^(#‘𝐹))(𝑃𝑘) ≠ (𝑃‘(𝑘 + 1))))
455, 44syl6bi 243 . . 3 (𝐹(Walks‘𝐺)𝑃 → (𝐹(Walks‘𝐺)𝑃 → (𝐼:dom 𝐼⟶{𝑥 ∈ 𝒫 𝑉 ∣ 2 ≤ (#‘𝑥)} → ∀𝑘 ∈ (0..^(#‘𝐹))(𝑃𝑘) ≠ (𝑃‘(𝑘 + 1)))))
4645pm2.43i 52 . 2 (𝐹(Walks‘𝐺)𝑃 → (𝐼:dom 𝐼⟶{𝑥 ∈ 𝒫 𝑉 ∣ 2 ≤ (#‘𝑥)} → ∀𝑘 ∈ (0..^(#‘𝐹))(𝑃𝑘) ≠ (𝑃‘(𝑘 + 1))))
4746imp 445 1 ((𝐹(Walks‘𝐺)𝑃𝐼:dom 𝐼⟶{𝑥 ∈ 𝒫 𝑉 ∣ 2 ≤ (#‘𝑥)}) → ∀𝑘 ∈ (0..^(#‘𝐹))(𝑃𝑘) ≠ (𝑃‘(𝑘 + 1)))
Colors of variables: wff setvar class
Syntax hints:  ¬ wn 3  wi 4  wb 196  wa 384  if-wif 1012  w3a 1037   = wceq 1483  wcel 1990  wne 2794  wral 2912  {crab 2916  Vcvv 3200  wss 3574  𝒫 cpw 4158  {csn 4177  {cpr 4179   class class class wbr 4653  dom cdm 5114  wf 5884  cfv 5888  (class class class)co 6650  0cc0 9936  1c1 9937   + caddc 9939   < clt 10074  cle 10075  2c2 11070  ...cfz 12326  ..^cfzo 12465  #chash 13117  Word cword 13291  Vtxcvtx 25874  iEdgciedg 25875  Walkscwlks 26492
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1722  ax-4 1737  ax-5 1839  ax-6 1888  ax-7 1935  ax-8 1992  ax-9 1999  ax-10 2019  ax-11 2034  ax-12 2047  ax-13 2246  ax-ext 2602  ax-rep 4771  ax-sep 4781  ax-nul 4789  ax-pow 4843  ax-pr 4906  ax-un 6949  ax-cnex 9992  ax-resscn 9993  ax-1cn 9994  ax-icn 9995  ax-addcl 9996  ax-addrcl 9997  ax-mulcl 9998  ax-mulrcl 9999  ax-mulcom 10000  ax-addass 10001  ax-mulass 10002  ax-distr 10003  ax-i2m1 10004  ax-1ne0 10005  ax-1rid 10006  ax-rnegex 10007  ax-rrecex 10008  ax-cnre 10009  ax-pre-lttri 10010  ax-pre-lttrn 10011  ax-pre-ltadd 10012  ax-pre-mulgt0 10013
This theorem depends on definitions:  df-bi 197  df-or 385  df-an 386  df-ifp 1013  df-3or 1038  df-3an 1039  df-tru 1486  df-ex 1705  df-nf 1710  df-sb 1881  df-eu 2474  df-mo 2475  df-clab 2609  df-cleq 2615  df-clel 2618  df-nfc 2753  df-ne 2795  df-nel 2898  df-ral 2917  df-rex 2918  df-reu 2919  df-rab 2921  df-v 3202  df-sbc 3436  df-csb 3534  df-dif 3577  df-un 3579  df-in 3581  df-ss 3588  df-pss 3590  df-nul 3916  df-if 4087  df-pw 4160  df-sn 4178  df-pr 4180  df-tp 4182  df-op 4184  df-uni 4437  df-int 4476  df-iun 4522  df-br 4654  df-opab 4713  df-mpt 4730  df-tr 4753  df-id 5024  df-eprel 5029  df-po 5035  df-so 5036  df-fr 5073  df-we 5075  df-xp 5120  df-rel 5121  df-cnv 5122  df-co 5123  df-dm 5124  df-rn 5125  df-res 5126  df-ima 5127  df-pred 5680  df-ord 5726  df-on 5727  df-lim 5728  df-suc 5729  df-iota 5851  df-fun 5890  df-fn 5891  df-f 5892  df-f1 5893  df-fo 5894  df-f1o 5895  df-fv 5896  df-riota 6611  df-ov 6653  df-oprab 6654  df-mpt2 6655  df-om 7066  df-1st 7168  df-2nd 7169  df-wrecs 7407  df-recs 7468  df-rdg 7506  df-1o 7560  df-er 7742  df-map 7859  df-pm 7860  df-en 7956  df-dom 7957  df-sdom 7958  df-fin 7959  df-card 8765  df-pnf 10076  df-mnf 10077  df-xr 10078  df-ltxr 10079  df-le 10080  df-sub 10268  df-neg 10269  df-nn 11021  df-2 11079  df-n0 11293  df-z 11378  df-uz 11688  df-fz 12327  df-fzo 12466  df-hash 13118  df-word 13299  df-wlks 26495
This theorem is referenced by:  lfgriswlk  26585
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