Metamath Proof Explorer


Theorem upgrimpthslem1

Description: Lemma 1 for upgrimpths . (Contributed by AV, 30-Oct-2025)

Ref Expression
Hypotheses upgrimwlk.i ⊢ I = iEdg ⁡ G
upgrimwlk.j ⊢ J = iEdg ⁡ H
upgrimwlk.g ⊢ φ → G ∈ USHGraph
upgrimwlk.h ⊢ φ → H ∈ USHGraph
upgrimwlk.n ⊢ φ → N ∈ G GraphIso H
upgrimwlk.e ⊢ E = x ∈ dom ⁡ F ⟼ J -1 ⁡ N I ⁡ F ⁡ x
upgrimpths.p ⊢ φ → F Paths ⁡ G P
Assertion upgrimpthslem1 ⊢ φ → Fun ⁡ N ∘ P ↾ 1 ..^ F -1

Proof

Step Hyp Ref Expression
1 upgrimwlk.i ⊢ I = iEdg ⁡ G
2 upgrimwlk.j ⊢ J = iEdg ⁡ H
3 upgrimwlk.g ⊢ φ → G ∈ USHGraph
4 upgrimwlk.h ⊢ φ → H ∈ USHGraph
5 upgrimwlk.n ⊢ φ → N ∈ G GraphIso H
6 upgrimwlk.e ⊢ E = x ∈ dom ⁡ F ⟼ J -1 ⁡ N I ⁡ F ⁡ x
7 upgrimpths.p ⊢ φ → F Paths ⁡ G P
8 ispth ⊢ F Paths ⁡ G P ↔ F Trails ⁡ G P ∧ Fun ⁡ P ↾ 1 ..^ F -1 ∧ P 0 F ∩ P 1 ..^ F = ∅
9 8 simp2bi ⊢ F Paths ⁡ G P → Fun ⁡ P ↾ 1 ..^ F -1
10 7 9 syl ⊢ φ → Fun ⁡ P ↾ 1 ..^ F -1
11 eqid ⊢ Vtx ⁡ G = Vtx ⁡ G
12 eqid ⊢ Vtx ⁡ H = Vtx ⁡ H
13 11 12 grimf1o ⊢ N ∈ G GraphIso H → N : Vtx ⁡ G ⟶ 1-1 onto Vtx ⁡ H
14 dff1o3 ⊢ N : Vtx ⁡ G ⟶ 1-1 onto Vtx ⁡ H ↔ N : Vtx ⁡ G ⟶ onto Vtx ⁡ H ∧ Fun ⁡ N -1
15 14 simprbi ⊢ N : Vtx ⁡ G ⟶ 1-1 onto Vtx ⁡ H → Fun ⁡ N -1
16 5 13 15 3syl ⊢ φ → Fun ⁡ N -1
17 funco ⊢ Fun ⁡ P ↾ 1 ..^ F -1 ∧ Fun ⁡ N -1 → Fun ⁡ P ↾ 1 ..^ F -1 ∘ N -1
18 10 16 17 syl2anc ⊢ φ → Fun ⁡ P ↾ 1 ..^ F -1 ∘ N -1
19 resco ⊢ N ∘ P ↾ 1 ..^ F = N ∘ P ↾ 1 ..^ F
20 19 cnveqi ⊢ N ∘ P ↾ 1 ..^ F -1 = N ∘ P ↾ 1 ..^ F -1
21 cnvco ⊢ N ∘ P ↾ 1 ..^ F -1 = P ↾ 1 ..^ F -1 ∘ N -1
22 20 21 eqtri ⊢ N ∘ P ↾ 1 ..^ F -1 = P ↾ 1 ..^ F -1 ∘ N -1
23 22 funeqi ⊢ Fun ⁡ N ∘ P ↾ 1 ..^ F -1 ↔ Fun ⁡ P ↾ 1 ..^ F -1 ∘ N -1
24 18 23 sylibr ⊢ φ → Fun ⁡ N ∘ P ↾ 1 ..^ F -1