| Step | Hyp | Ref | Expression | 
						
							| 1 |  | ip2eqi.1 | ⊢ 𝑋  =  ( BaseSet ‘ 𝑈 ) | 
						
							| 2 |  | ip2eqi.7 | ⊢ 𝑃  =  ( ·𝑖OLD ‘ 𝑈 ) | 
						
							| 3 |  | ip2eqi.u | ⊢ 𝑈  ∈  CPreHilOLD | 
						
							| 4 |  | r19.26-2 | ⊢ ( ∀ 𝑥  ∈  𝑋 ∀ 𝑦  ∈  𝑌 ( ( ( 𝑇 ‘ 𝑥 ) 𝑄 𝑦 )  =  ( 𝑥 𝑃 ( 𝑠 ‘ 𝑦 ) )  ∧  ( ( 𝑇 ‘ 𝑥 ) 𝑄 𝑦 )  =  ( 𝑥 𝑃 ( 𝑡 ‘ 𝑦 ) ) )  ↔  ( ∀ 𝑥  ∈  𝑋 ∀ 𝑦  ∈  𝑌 ( ( 𝑇 ‘ 𝑥 ) 𝑄 𝑦 )  =  ( 𝑥 𝑃 ( 𝑠 ‘ 𝑦 ) )  ∧  ∀ 𝑥  ∈  𝑋 ∀ 𝑦  ∈  𝑌 ( ( 𝑇 ‘ 𝑥 ) 𝑄 𝑦 )  =  ( 𝑥 𝑃 ( 𝑡 ‘ 𝑦 ) ) ) ) | 
						
							| 5 |  | eqtr2 | ⊢ ( ( ( ( 𝑇 ‘ 𝑥 ) 𝑄 𝑦 )  =  ( 𝑥 𝑃 ( 𝑠 ‘ 𝑦 ) )  ∧  ( ( 𝑇 ‘ 𝑥 ) 𝑄 𝑦 )  =  ( 𝑥 𝑃 ( 𝑡 ‘ 𝑦 ) ) )  →  ( 𝑥 𝑃 ( 𝑠 ‘ 𝑦 ) )  =  ( 𝑥 𝑃 ( 𝑡 ‘ 𝑦 ) ) ) | 
						
							| 6 | 5 | 2ralimi | ⊢ ( ∀ 𝑥  ∈  𝑋 ∀ 𝑦  ∈  𝑌 ( ( ( 𝑇 ‘ 𝑥 ) 𝑄 𝑦 )  =  ( 𝑥 𝑃 ( 𝑠 ‘ 𝑦 ) )  ∧  ( ( 𝑇 ‘ 𝑥 ) 𝑄 𝑦 )  =  ( 𝑥 𝑃 ( 𝑡 ‘ 𝑦 ) ) )  →  ∀ 𝑥  ∈  𝑋 ∀ 𝑦  ∈  𝑌 ( 𝑥 𝑃 ( 𝑠 ‘ 𝑦 ) )  =  ( 𝑥 𝑃 ( 𝑡 ‘ 𝑦 ) ) ) | 
						
							| 7 | 4 6 | sylbir | ⊢ ( ( ∀ 𝑥  ∈  𝑋 ∀ 𝑦  ∈  𝑌 ( ( 𝑇 ‘ 𝑥 ) 𝑄 𝑦 )  =  ( 𝑥 𝑃 ( 𝑠 ‘ 𝑦 ) )  ∧  ∀ 𝑥  ∈  𝑋 ∀ 𝑦  ∈  𝑌 ( ( 𝑇 ‘ 𝑥 ) 𝑄 𝑦 )  =  ( 𝑥 𝑃 ( 𝑡 ‘ 𝑦 ) ) )  →  ∀ 𝑥  ∈  𝑋 ∀ 𝑦  ∈  𝑌 ( 𝑥 𝑃 ( 𝑠 ‘ 𝑦 ) )  =  ( 𝑥 𝑃 ( 𝑡 ‘ 𝑦 ) ) ) | 
						
							| 8 | 1 2 3 | phoeqi | ⊢ ( ( 𝑠 : 𝑌 ⟶ 𝑋  ∧  𝑡 : 𝑌 ⟶ 𝑋 )  →  ( ∀ 𝑥  ∈  𝑋 ∀ 𝑦  ∈  𝑌 ( 𝑥 𝑃 ( 𝑠 ‘ 𝑦 ) )  =  ( 𝑥 𝑃 ( 𝑡 ‘ 𝑦 ) )  ↔  𝑠  =  𝑡 ) ) | 
						
							| 9 | 8 | biimpa | ⊢ ( ( ( 𝑠 : 𝑌 ⟶ 𝑋  ∧  𝑡 : 𝑌 ⟶ 𝑋 )  ∧  ∀ 𝑥  ∈  𝑋 ∀ 𝑦  ∈  𝑌 ( 𝑥 𝑃 ( 𝑠 ‘ 𝑦 ) )  =  ( 𝑥 𝑃 ( 𝑡 ‘ 𝑦 ) ) )  →  𝑠  =  𝑡 ) | 
						
							| 10 | 7 9 | sylan2 | ⊢ ( ( ( 𝑠 : 𝑌 ⟶ 𝑋  ∧  𝑡 : 𝑌 ⟶ 𝑋 )  ∧  ( ∀ 𝑥  ∈  𝑋 ∀ 𝑦  ∈  𝑌 ( ( 𝑇 ‘ 𝑥 ) 𝑄 𝑦 )  =  ( 𝑥 𝑃 ( 𝑠 ‘ 𝑦 ) )  ∧  ∀ 𝑥  ∈  𝑋 ∀ 𝑦  ∈  𝑌 ( ( 𝑇 ‘ 𝑥 ) 𝑄 𝑦 )  =  ( 𝑥 𝑃 ( 𝑡 ‘ 𝑦 ) ) ) )  →  𝑠  =  𝑡 ) | 
						
							| 11 | 10 | an4s | ⊢ ( ( ( 𝑠 : 𝑌 ⟶ 𝑋  ∧  ∀ 𝑥  ∈  𝑋 ∀ 𝑦  ∈  𝑌 ( ( 𝑇 ‘ 𝑥 ) 𝑄 𝑦 )  =  ( 𝑥 𝑃 ( 𝑠 ‘ 𝑦 ) ) )  ∧  ( 𝑡 : 𝑌 ⟶ 𝑋  ∧  ∀ 𝑥  ∈  𝑋 ∀ 𝑦  ∈  𝑌 ( ( 𝑇 ‘ 𝑥 ) 𝑄 𝑦 )  =  ( 𝑥 𝑃 ( 𝑡 ‘ 𝑦 ) ) ) )  →  𝑠  =  𝑡 ) | 
						
							| 12 | 11 | gen2 | ⊢ ∀ 𝑠 ∀ 𝑡 ( ( ( 𝑠 : 𝑌 ⟶ 𝑋  ∧  ∀ 𝑥  ∈  𝑋 ∀ 𝑦  ∈  𝑌 ( ( 𝑇 ‘ 𝑥 ) 𝑄 𝑦 )  =  ( 𝑥 𝑃 ( 𝑠 ‘ 𝑦 ) ) )  ∧  ( 𝑡 : 𝑌 ⟶ 𝑋  ∧  ∀ 𝑥  ∈  𝑋 ∀ 𝑦  ∈  𝑌 ( ( 𝑇 ‘ 𝑥 ) 𝑄 𝑦 )  =  ( 𝑥 𝑃 ( 𝑡 ‘ 𝑦 ) ) ) )  →  𝑠  =  𝑡 ) | 
						
							| 13 |  | feq1 | ⊢ ( 𝑠  =  𝑡  →  ( 𝑠 : 𝑌 ⟶ 𝑋  ↔  𝑡 : 𝑌 ⟶ 𝑋 ) ) | 
						
							| 14 |  | fveq1 | ⊢ ( 𝑠  =  𝑡  →  ( 𝑠 ‘ 𝑦 )  =  ( 𝑡 ‘ 𝑦 ) ) | 
						
							| 15 | 14 | oveq2d | ⊢ ( 𝑠  =  𝑡  →  ( 𝑥 𝑃 ( 𝑠 ‘ 𝑦 ) )  =  ( 𝑥 𝑃 ( 𝑡 ‘ 𝑦 ) ) ) | 
						
							| 16 | 15 | eqeq2d | ⊢ ( 𝑠  =  𝑡  →  ( ( ( 𝑇 ‘ 𝑥 ) 𝑄 𝑦 )  =  ( 𝑥 𝑃 ( 𝑠 ‘ 𝑦 ) )  ↔  ( ( 𝑇 ‘ 𝑥 ) 𝑄 𝑦 )  =  ( 𝑥 𝑃 ( 𝑡 ‘ 𝑦 ) ) ) ) | 
						
							| 17 | 16 | 2ralbidv | ⊢ ( 𝑠  =  𝑡  →  ( ∀ 𝑥  ∈  𝑋 ∀ 𝑦  ∈  𝑌 ( ( 𝑇 ‘ 𝑥 ) 𝑄 𝑦 )  =  ( 𝑥 𝑃 ( 𝑠 ‘ 𝑦 ) )  ↔  ∀ 𝑥  ∈  𝑋 ∀ 𝑦  ∈  𝑌 ( ( 𝑇 ‘ 𝑥 ) 𝑄 𝑦 )  =  ( 𝑥 𝑃 ( 𝑡 ‘ 𝑦 ) ) ) ) | 
						
							| 18 | 13 17 | anbi12d | ⊢ ( 𝑠  =  𝑡  →  ( ( 𝑠 : 𝑌 ⟶ 𝑋  ∧  ∀ 𝑥  ∈  𝑋 ∀ 𝑦  ∈  𝑌 ( ( 𝑇 ‘ 𝑥 ) 𝑄 𝑦 )  =  ( 𝑥 𝑃 ( 𝑠 ‘ 𝑦 ) ) )  ↔  ( 𝑡 : 𝑌 ⟶ 𝑋  ∧  ∀ 𝑥  ∈  𝑋 ∀ 𝑦  ∈  𝑌 ( ( 𝑇 ‘ 𝑥 ) 𝑄 𝑦 )  =  ( 𝑥 𝑃 ( 𝑡 ‘ 𝑦 ) ) ) ) ) | 
						
							| 19 | 18 | mo4 | ⊢ ( ∃* 𝑠 ( 𝑠 : 𝑌 ⟶ 𝑋  ∧  ∀ 𝑥  ∈  𝑋 ∀ 𝑦  ∈  𝑌 ( ( 𝑇 ‘ 𝑥 ) 𝑄 𝑦 )  =  ( 𝑥 𝑃 ( 𝑠 ‘ 𝑦 ) ) )  ↔  ∀ 𝑠 ∀ 𝑡 ( ( ( 𝑠 : 𝑌 ⟶ 𝑋  ∧  ∀ 𝑥  ∈  𝑋 ∀ 𝑦  ∈  𝑌 ( ( 𝑇 ‘ 𝑥 ) 𝑄 𝑦 )  =  ( 𝑥 𝑃 ( 𝑠 ‘ 𝑦 ) ) )  ∧  ( 𝑡 : 𝑌 ⟶ 𝑋  ∧  ∀ 𝑥  ∈  𝑋 ∀ 𝑦  ∈  𝑌 ( ( 𝑇 ‘ 𝑥 ) 𝑄 𝑦 )  =  ( 𝑥 𝑃 ( 𝑡 ‘ 𝑦 ) ) ) )  →  𝑠  =  𝑡 ) ) | 
						
							| 20 | 12 19 | mpbir | ⊢ ∃* 𝑠 ( 𝑠 : 𝑌 ⟶ 𝑋  ∧  ∀ 𝑥  ∈  𝑋 ∀ 𝑦  ∈  𝑌 ( ( 𝑇 ‘ 𝑥 ) 𝑄 𝑦 )  =  ( 𝑥 𝑃 ( 𝑠 ‘ 𝑦 ) ) ) |