| Step | 
						Hyp | 
						Ref | 
						Expression | 
					
						
							| 1 | 
							
								
							 | 
							resf1st.f | 
							⊢ ( 𝜑  →  𝐹  ∈  𝑉 )  | 
						
						
							| 2 | 
							
								
							 | 
							resf1st.h | 
							⊢ ( 𝜑  →  𝐻  ∈  𝑊 )  | 
						
						
							| 3 | 
							
								
							 | 
							resf1st.s | 
							⊢ ( 𝜑  →  𝐻  Fn  ( 𝑆  ×  𝑆 ) )  | 
						
						
							| 4 | 
							
								
							 | 
							resf2nd.x | 
							⊢ ( 𝜑  →  𝑋  ∈  𝑆 )  | 
						
						
							| 5 | 
							
								
							 | 
							resf2nd.y | 
							⊢ ( 𝜑  →  𝑌  ∈  𝑆 )  | 
						
						
							| 6 | 
							
								
							 | 
							df-ov | 
							⊢ ( 𝑋 ( 2nd  ‘ ( 𝐹  ↾f  𝐻 ) ) 𝑌 )  =  ( ( 2nd  ‘ ( 𝐹  ↾f  𝐻 ) ) ‘ 〈 𝑋 ,  𝑌 〉 )  | 
						
						
							| 7 | 
							
								1 2
							 | 
							resfval | 
							⊢ ( 𝜑  →  ( 𝐹  ↾f  𝐻 )  =  〈 ( ( 1st  ‘ 𝐹 )  ↾  dom  dom  𝐻 ) ,  ( 𝑧  ∈  dom  𝐻  ↦  ( ( ( 2nd  ‘ 𝐹 ) ‘ 𝑧 )  ↾  ( 𝐻 ‘ 𝑧 ) ) ) 〉 )  | 
						
						
							| 8 | 
							
								7
							 | 
							fveq2d | 
							⊢ ( 𝜑  →  ( 2nd  ‘ ( 𝐹  ↾f  𝐻 ) )  =  ( 2nd  ‘ 〈 ( ( 1st  ‘ 𝐹 )  ↾  dom  dom  𝐻 ) ,  ( 𝑧  ∈  dom  𝐻  ↦  ( ( ( 2nd  ‘ 𝐹 ) ‘ 𝑧 )  ↾  ( 𝐻 ‘ 𝑧 ) ) ) 〉 ) )  | 
						
						
							| 9 | 
							
								
							 | 
							fvex | 
							⊢ ( 1st  ‘ 𝐹 )  ∈  V  | 
						
						
							| 10 | 
							
								9
							 | 
							resex | 
							⊢ ( ( 1st  ‘ 𝐹 )  ↾  dom  dom  𝐻 )  ∈  V  | 
						
						
							| 11 | 
							
								
							 | 
							dmexg | 
							⊢ ( 𝐻  ∈  𝑊  →  dom  𝐻  ∈  V )  | 
						
						
							| 12 | 
							
								
							 | 
							mptexg | 
							⊢ ( dom  𝐻  ∈  V  →  ( 𝑧  ∈  dom  𝐻  ↦  ( ( ( 2nd  ‘ 𝐹 ) ‘ 𝑧 )  ↾  ( 𝐻 ‘ 𝑧 ) ) )  ∈  V )  | 
						
						
							| 13 | 
							
								2 11 12
							 | 
							3syl | 
							⊢ ( 𝜑  →  ( 𝑧  ∈  dom  𝐻  ↦  ( ( ( 2nd  ‘ 𝐹 ) ‘ 𝑧 )  ↾  ( 𝐻 ‘ 𝑧 ) ) )  ∈  V )  | 
						
						
							| 14 | 
							
								
							 | 
							op2ndg | 
							⊢ ( ( ( ( 1st  ‘ 𝐹 )  ↾  dom  dom  𝐻 )  ∈  V  ∧  ( 𝑧  ∈  dom  𝐻  ↦  ( ( ( 2nd  ‘ 𝐹 ) ‘ 𝑧 )  ↾  ( 𝐻 ‘ 𝑧 ) ) )  ∈  V )  →  ( 2nd  ‘ 〈 ( ( 1st  ‘ 𝐹 )  ↾  dom  dom  𝐻 ) ,  ( 𝑧  ∈  dom  𝐻  ↦  ( ( ( 2nd  ‘ 𝐹 ) ‘ 𝑧 )  ↾  ( 𝐻 ‘ 𝑧 ) ) ) 〉 )  =  ( 𝑧  ∈  dom  𝐻  ↦  ( ( ( 2nd  ‘ 𝐹 ) ‘ 𝑧 )  ↾  ( 𝐻 ‘ 𝑧 ) ) ) )  | 
						
						
							| 15 | 
							
								10 13 14
							 | 
							sylancr | 
							⊢ ( 𝜑  →  ( 2nd  ‘ 〈 ( ( 1st  ‘ 𝐹 )  ↾  dom  dom  𝐻 ) ,  ( 𝑧  ∈  dom  𝐻  ↦  ( ( ( 2nd  ‘ 𝐹 ) ‘ 𝑧 )  ↾  ( 𝐻 ‘ 𝑧 ) ) ) 〉 )  =  ( 𝑧  ∈  dom  𝐻  ↦  ( ( ( 2nd  ‘ 𝐹 ) ‘ 𝑧 )  ↾  ( 𝐻 ‘ 𝑧 ) ) ) )  | 
						
						
							| 16 | 
							
								8 15
							 | 
							eqtrd | 
							⊢ ( 𝜑  →  ( 2nd  ‘ ( 𝐹  ↾f  𝐻 ) )  =  ( 𝑧  ∈  dom  𝐻  ↦  ( ( ( 2nd  ‘ 𝐹 ) ‘ 𝑧 )  ↾  ( 𝐻 ‘ 𝑧 ) ) ) )  | 
						
						
							| 17 | 
							
								
							 | 
							simpr | 
							⊢ ( ( 𝜑  ∧  𝑧  =  〈 𝑋 ,  𝑌 〉 )  →  𝑧  =  〈 𝑋 ,  𝑌 〉 )  | 
						
						
							| 18 | 
							
								17
							 | 
							fveq2d | 
							⊢ ( ( 𝜑  ∧  𝑧  =  〈 𝑋 ,  𝑌 〉 )  →  ( ( 2nd  ‘ 𝐹 ) ‘ 𝑧 )  =  ( ( 2nd  ‘ 𝐹 ) ‘ 〈 𝑋 ,  𝑌 〉 ) )  | 
						
						
							| 19 | 
							
								
							 | 
							df-ov | 
							⊢ ( 𝑋 ( 2nd  ‘ 𝐹 ) 𝑌 )  =  ( ( 2nd  ‘ 𝐹 ) ‘ 〈 𝑋 ,  𝑌 〉 )  | 
						
						
							| 20 | 
							
								18 19
							 | 
							eqtr4di | 
							⊢ ( ( 𝜑  ∧  𝑧  =  〈 𝑋 ,  𝑌 〉 )  →  ( ( 2nd  ‘ 𝐹 ) ‘ 𝑧 )  =  ( 𝑋 ( 2nd  ‘ 𝐹 ) 𝑌 ) )  | 
						
						
							| 21 | 
							
								17
							 | 
							fveq2d | 
							⊢ ( ( 𝜑  ∧  𝑧  =  〈 𝑋 ,  𝑌 〉 )  →  ( 𝐻 ‘ 𝑧 )  =  ( 𝐻 ‘ 〈 𝑋 ,  𝑌 〉 ) )  | 
						
						
							| 22 | 
							
								
							 | 
							df-ov | 
							⊢ ( 𝑋 𝐻 𝑌 )  =  ( 𝐻 ‘ 〈 𝑋 ,  𝑌 〉 )  | 
						
						
							| 23 | 
							
								21 22
							 | 
							eqtr4di | 
							⊢ ( ( 𝜑  ∧  𝑧  =  〈 𝑋 ,  𝑌 〉 )  →  ( 𝐻 ‘ 𝑧 )  =  ( 𝑋 𝐻 𝑌 ) )  | 
						
						
							| 24 | 
							
								20 23
							 | 
							reseq12d | 
							⊢ ( ( 𝜑  ∧  𝑧  =  〈 𝑋 ,  𝑌 〉 )  →  ( ( ( 2nd  ‘ 𝐹 ) ‘ 𝑧 )  ↾  ( 𝐻 ‘ 𝑧 ) )  =  ( ( 𝑋 ( 2nd  ‘ 𝐹 ) 𝑌 )  ↾  ( 𝑋 𝐻 𝑌 ) ) )  | 
						
						
							| 25 | 
							
								4 5
							 | 
							opelxpd | 
							⊢ ( 𝜑  →  〈 𝑋 ,  𝑌 〉  ∈  ( 𝑆  ×  𝑆 ) )  | 
						
						
							| 26 | 
							
								3
							 | 
							fndmd | 
							⊢ ( 𝜑  →  dom  𝐻  =  ( 𝑆  ×  𝑆 ) )  | 
						
						
							| 27 | 
							
								25 26
							 | 
							eleqtrrd | 
							⊢ ( 𝜑  →  〈 𝑋 ,  𝑌 〉  ∈  dom  𝐻 )  | 
						
						
							| 28 | 
							
								
							 | 
							ovex | 
							⊢ ( 𝑋 ( 2nd  ‘ 𝐹 ) 𝑌 )  ∈  V  | 
						
						
							| 29 | 
							
								28
							 | 
							resex | 
							⊢ ( ( 𝑋 ( 2nd  ‘ 𝐹 ) 𝑌 )  ↾  ( 𝑋 𝐻 𝑌 ) )  ∈  V  | 
						
						
							| 30 | 
							
								29
							 | 
							a1i | 
							⊢ ( 𝜑  →  ( ( 𝑋 ( 2nd  ‘ 𝐹 ) 𝑌 )  ↾  ( 𝑋 𝐻 𝑌 ) )  ∈  V )  | 
						
						
							| 31 | 
							
								16 24 27 30
							 | 
							fvmptd | 
							⊢ ( 𝜑  →  ( ( 2nd  ‘ ( 𝐹  ↾f  𝐻 ) ) ‘ 〈 𝑋 ,  𝑌 〉 )  =  ( ( 𝑋 ( 2nd  ‘ 𝐹 ) 𝑌 )  ↾  ( 𝑋 𝐻 𝑌 ) ) )  | 
						
						
							| 32 | 
							
								6 31
							 | 
							eqtrid | 
							⊢ ( 𝜑  →  ( 𝑋 ( 2nd  ‘ ( 𝐹  ↾f  𝐻 ) ) 𝑌 )  =  ( ( 𝑋 ( 2nd  ‘ 𝐹 ) 𝑌 )  ↾  ( 𝑋 𝐻 𝑌 ) ) )  |