| Step | Hyp | Ref | Expression | 
						
							| 1 |  | pi1co.p | ⊢ 𝑃  =  ( 𝐽  π1  𝐴 ) | 
						
							| 2 |  | pi1co.q | ⊢ 𝑄  =  ( 𝐾  π1  𝐵 ) | 
						
							| 3 |  | pi1co.v | ⊢ 𝑉  =  ( Base ‘ 𝑃 ) | 
						
							| 4 |  | pi1co.g | ⊢ 𝐺  =  ran  ( 𝑔  ∈  ∪  𝑉  ↦  〈 [ 𝑔 ] (  ≃ph ‘ 𝐽 ) ,  [ ( 𝐹  ∘  𝑔 ) ] (  ≃ph ‘ 𝐾 ) 〉 ) | 
						
							| 5 |  | pi1co.j | ⊢ ( 𝜑  →  𝐽  ∈  ( TopOn ‘ 𝑋 ) ) | 
						
							| 6 |  | pi1co.f | ⊢ ( 𝜑  →  𝐹  ∈  ( 𝐽  Cn  𝐾 ) ) | 
						
							| 7 |  | pi1co.a | ⊢ ( 𝜑  →  𝐴  ∈  𝑋 ) | 
						
							| 8 |  | pi1co.b | ⊢ ( 𝜑  →  ( 𝐹 ‘ 𝐴 )  =  𝐵 ) | 
						
							| 9 |  | fvex | ⊢ (  ≃ph ‘ 𝐽 )  ∈  V | 
						
							| 10 |  | ecexg | ⊢ ( (  ≃ph ‘ 𝐽 )  ∈  V  →  [ 𝑔 ] (  ≃ph ‘ 𝐽 )  ∈  V ) | 
						
							| 11 | 9 10 | mp1i | ⊢ ( ( 𝜑  ∧  𝑔  ∈  ∪  𝑉 )  →  [ 𝑔 ] (  ≃ph ‘ 𝐽 )  ∈  V ) | 
						
							| 12 |  | fvex | ⊢ (  ≃ph ‘ 𝐾 )  ∈  V | 
						
							| 13 |  | ecexg | ⊢ ( (  ≃ph ‘ 𝐾 )  ∈  V  →  [ ( 𝐹  ∘  𝑔 ) ] (  ≃ph ‘ 𝐾 )  ∈  V ) | 
						
							| 14 | 12 13 | mp1i | ⊢ ( ( 𝜑  ∧  𝑔  ∈  ∪  𝑉 )  →  [ ( 𝐹  ∘  𝑔 ) ] (  ≃ph ‘ 𝐾 )  ∈  V ) | 
						
							| 15 |  | eceq1 | ⊢ ( 𝑔  =  𝑇  →  [ 𝑔 ] (  ≃ph ‘ 𝐽 )  =  [ 𝑇 ] (  ≃ph ‘ 𝐽 ) ) | 
						
							| 16 |  | coeq2 | ⊢ ( 𝑔  =  𝑇  →  ( 𝐹  ∘  𝑔 )  =  ( 𝐹  ∘  𝑇 ) ) | 
						
							| 17 | 16 | eceq1d | ⊢ ( 𝑔  =  𝑇  →  [ ( 𝐹  ∘  𝑔 ) ] (  ≃ph ‘ 𝐾 )  =  [ ( 𝐹  ∘  𝑇 ) ] (  ≃ph ‘ 𝐾 ) ) | 
						
							| 18 | 1 2 3 4 5 6 7 8 | pi1cof | ⊢ ( 𝜑  →  𝐺 : 𝑉 ⟶ ( Base ‘ 𝑄 ) ) | 
						
							| 19 | 18 | ffund | ⊢ ( 𝜑  →  Fun  𝐺 ) | 
						
							| 20 | 4 11 14 15 17 19 | fliftval | ⊢ ( ( 𝜑  ∧  𝑇  ∈  ∪  𝑉 )  →  ( 𝐺 ‘ [ 𝑇 ] (  ≃ph ‘ 𝐽 ) )  =  [ ( 𝐹  ∘  𝑇 ) ] (  ≃ph ‘ 𝐾 ) ) |