| Step | 
						Hyp | 
						Ref | 
						Expression | 
					
						
							| 1 | 
							
								
							 | 
							cofuval2.b | 
							⊢ 𝐵  =  ( Base ‘ 𝐶 )  | 
						
						
							| 2 | 
							
								
							 | 
							cofuval2.f | 
							⊢ ( 𝜑  →  𝐹 ( 𝐶  Func  𝐷 ) 𝐺 )  | 
						
						
							| 3 | 
							
								
							 | 
							cofuval2.x | 
							⊢ ( 𝜑  →  𝐻 ( 𝐷  Func  𝐸 ) 𝐾 )  | 
						
						
							| 4 | 
							
								
							 | 
							df-br | 
							⊢ ( 𝐹 ( 𝐶  Func  𝐷 ) 𝐺  ↔  〈 𝐹 ,  𝐺 〉  ∈  ( 𝐶  Func  𝐷 ) )  | 
						
						
							| 5 | 
							
								2 4
							 | 
							sylib | 
							⊢ ( 𝜑  →  〈 𝐹 ,  𝐺 〉  ∈  ( 𝐶  Func  𝐷 ) )  | 
						
						
							| 6 | 
							
								
							 | 
							df-br | 
							⊢ ( 𝐻 ( 𝐷  Func  𝐸 ) 𝐾  ↔  〈 𝐻 ,  𝐾 〉  ∈  ( 𝐷  Func  𝐸 ) )  | 
						
						
							| 7 | 
							
								3 6
							 | 
							sylib | 
							⊢ ( 𝜑  →  〈 𝐻 ,  𝐾 〉  ∈  ( 𝐷  Func  𝐸 ) )  | 
						
						
							| 8 | 
							
								1 5 7
							 | 
							cofuval | 
							⊢ ( 𝜑  →  ( 〈 𝐻 ,  𝐾 〉  ∘func  〈 𝐹 ,  𝐺 〉 )  =  〈 ( ( 1st  ‘ 〈 𝐻 ,  𝐾 〉 )  ∘  ( 1st  ‘ 〈 𝐹 ,  𝐺 〉 ) ) ,  ( 𝑥  ∈  𝐵 ,  𝑦  ∈  𝐵  ↦  ( ( ( ( 1st  ‘ 〈 𝐹 ,  𝐺 〉 ) ‘ 𝑥 ) ( 2nd  ‘ 〈 𝐻 ,  𝐾 〉 ) ( ( 1st  ‘ 〈 𝐹 ,  𝐺 〉 ) ‘ 𝑦 ) )  ∘  ( 𝑥 ( 2nd  ‘ 〈 𝐹 ,  𝐺 〉 ) 𝑦 ) ) ) 〉 )  | 
						
						
							| 9 | 
							
								
							 | 
							relfunc | 
							⊢ Rel  ( 𝐷  Func  𝐸 )  | 
						
						
							| 10 | 
							
								
							 | 
							brrelex12 | 
							⊢ ( ( Rel  ( 𝐷  Func  𝐸 )  ∧  𝐻 ( 𝐷  Func  𝐸 ) 𝐾 )  →  ( 𝐻  ∈  V  ∧  𝐾  ∈  V ) )  | 
						
						
							| 11 | 
							
								9 3 10
							 | 
							sylancr | 
							⊢ ( 𝜑  →  ( 𝐻  ∈  V  ∧  𝐾  ∈  V ) )  | 
						
						
							| 12 | 
							
								
							 | 
							op1stg | 
							⊢ ( ( 𝐻  ∈  V  ∧  𝐾  ∈  V )  →  ( 1st  ‘ 〈 𝐻 ,  𝐾 〉 )  =  𝐻 )  | 
						
						
							| 13 | 
							
								11 12
							 | 
							syl | 
							⊢ ( 𝜑  →  ( 1st  ‘ 〈 𝐻 ,  𝐾 〉 )  =  𝐻 )  | 
						
						
							| 14 | 
							
								
							 | 
							relfunc | 
							⊢ Rel  ( 𝐶  Func  𝐷 )  | 
						
						
							| 15 | 
							
								
							 | 
							brrelex12 | 
							⊢ ( ( Rel  ( 𝐶  Func  𝐷 )  ∧  𝐹 ( 𝐶  Func  𝐷 ) 𝐺 )  →  ( 𝐹  ∈  V  ∧  𝐺  ∈  V ) )  | 
						
						
							| 16 | 
							
								14 2 15
							 | 
							sylancr | 
							⊢ ( 𝜑  →  ( 𝐹  ∈  V  ∧  𝐺  ∈  V ) )  | 
						
						
							| 17 | 
							
								
							 | 
							op1stg | 
							⊢ ( ( 𝐹  ∈  V  ∧  𝐺  ∈  V )  →  ( 1st  ‘ 〈 𝐹 ,  𝐺 〉 )  =  𝐹 )  | 
						
						
							| 18 | 
							
								16 17
							 | 
							syl | 
							⊢ ( 𝜑  →  ( 1st  ‘ 〈 𝐹 ,  𝐺 〉 )  =  𝐹 )  | 
						
						
							| 19 | 
							
								13 18
							 | 
							coeq12d | 
							⊢ ( 𝜑  →  ( ( 1st  ‘ 〈 𝐻 ,  𝐾 〉 )  ∘  ( 1st  ‘ 〈 𝐹 ,  𝐺 〉 ) )  =  ( 𝐻  ∘  𝐹 ) )  | 
						
						
							| 20 | 
							
								
							 | 
							op2ndg | 
							⊢ ( ( 𝐻  ∈  V  ∧  𝐾  ∈  V )  →  ( 2nd  ‘ 〈 𝐻 ,  𝐾 〉 )  =  𝐾 )  | 
						
						
							| 21 | 
							
								11 20
							 | 
							syl | 
							⊢ ( 𝜑  →  ( 2nd  ‘ 〈 𝐻 ,  𝐾 〉 )  =  𝐾 )  | 
						
						
							| 22 | 
							
								21
							 | 
							3ad2ant1 | 
							⊢ ( ( 𝜑  ∧  𝑥  ∈  𝐵  ∧  𝑦  ∈  𝐵 )  →  ( 2nd  ‘ 〈 𝐻 ,  𝐾 〉 )  =  𝐾 )  | 
						
						
							| 23 | 
							
								18
							 | 
							3ad2ant1 | 
							⊢ ( ( 𝜑  ∧  𝑥  ∈  𝐵  ∧  𝑦  ∈  𝐵 )  →  ( 1st  ‘ 〈 𝐹 ,  𝐺 〉 )  =  𝐹 )  | 
						
						
							| 24 | 
							
								23
							 | 
							fveq1d | 
							⊢ ( ( 𝜑  ∧  𝑥  ∈  𝐵  ∧  𝑦  ∈  𝐵 )  →  ( ( 1st  ‘ 〈 𝐹 ,  𝐺 〉 ) ‘ 𝑥 )  =  ( 𝐹 ‘ 𝑥 ) )  | 
						
						
							| 25 | 
							
								23
							 | 
							fveq1d | 
							⊢ ( ( 𝜑  ∧  𝑥  ∈  𝐵  ∧  𝑦  ∈  𝐵 )  →  ( ( 1st  ‘ 〈 𝐹 ,  𝐺 〉 ) ‘ 𝑦 )  =  ( 𝐹 ‘ 𝑦 ) )  | 
						
						
							| 26 | 
							
								22 24 25
							 | 
							oveq123d | 
							⊢ ( ( 𝜑  ∧  𝑥  ∈  𝐵  ∧  𝑦  ∈  𝐵 )  →  ( ( ( 1st  ‘ 〈 𝐹 ,  𝐺 〉 ) ‘ 𝑥 ) ( 2nd  ‘ 〈 𝐻 ,  𝐾 〉 ) ( ( 1st  ‘ 〈 𝐹 ,  𝐺 〉 ) ‘ 𝑦 ) )  =  ( ( 𝐹 ‘ 𝑥 ) 𝐾 ( 𝐹 ‘ 𝑦 ) ) )  | 
						
						
							| 27 | 
							
								
							 | 
							op2ndg | 
							⊢ ( ( 𝐹  ∈  V  ∧  𝐺  ∈  V )  →  ( 2nd  ‘ 〈 𝐹 ,  𝐺 〉 )  =  𝐺 )  | 
						
						
							| 28 | 
							
								16 27
							 | 
							syl | 
							⊢ ( 𝜑  →  ( 2nd  ‘ 〈 𝐹 ,  𝐺 〉 )  =  𝐺 )  | 
						
						
							| 29 | 
							
								28
							 | 
							3ad2ant1 | 
							⊢ ( ( 𝜑  ∧  𝑥  ∈  𝐵  ∧  𝑦  ∈  𝐵 )  →  ( 2nd  ‘ 〈 𝐹 ,  𝐺 〉 )  =  𝐺 )  | 
						
						
							| 30 | 
							
								29
							 | 
							oveqd | 
							⊢ ( ( 𝜑  ∧  𝑥  ∈  𝐵  ∧  𝑦  ∈  𝐵 )  →  ( 𝑥 ( 2nd  ‘ 〈 𝐹 ,  𝐺 〉 ) 𝑦 )  =  ( 𝑥 𝐺 𝑦 ) )  | 
						
						
							| 31 | 
							
								26 30
							 | 
							coeq12d | 
							⊢ ( ( 𝜑  ∧  𝑥  ∈  𝐵  ∧  𝑦  ∈  𝐵 )  →  ( ( ( ( 1st  ‘ 〈 𝐹 ,  𝐺 〉 ) ‘ 𝑥 ) ( 2nd  ‘ 〈 𝐻 ,  𝐾 〉 ) ( ( 1st  ‘ 〈 𝐹 ,  𝐺 〉 ) ‘ 𝑦 ) )  ∘  ( 𝑥 ( 2nd  ‘ 〈 𝐹 ,  𝐺 〉 ) 𝑦 ) )  =  ( ( ( 𝐹 ‘ 𝑥 ) 𝐾 ( 𝐹 ‘ 𝑦 ) )  ∘  ( 𝑥 𝐺 𝑦 ) ) )  | 
						
						
							| 32 | 
							
								31
							 | 
							mpoeq3dva | 
							⊢ ( 𝜑  →  ( 𝑥  ∈  𝐵 ,  𝑦  ∈  𝐵  ↦  ( ( ( ( 1st  ‘ 〈 𝐹 ,  𝐺 〉 ) ‘ 𝑥 ) ( 2nd  ‘ 〈 𝐻 ,  𝐾 〉 ) ( ( 1st  ‘ 〈 𝐹 ,  𝐺 〉 ) ‘ 𝑦 ) )  ∘  ( 𝑥 ( 2nd  ‘ 〈 𝐹 ,  𝐺 〉 ) 𝑦 ) ) )  =  ( 𝑥  ∈  𝐵 ,  𝑦  ∈  𝐵  ↦  ( ( ( 𝐹 ‘ 𝑥 ) 𝐾 ( 𝐹 ‘ 𝑦 ) )  ∘  ( 𝑥 𝐺 𝑦 ) ) ) )  | 
						
						
							| 33 | 
							
								19 32
							 | 
							opeq12d | 
							⊢ ( 𝜑  →  〈 ( ( 1st  ‘ 〈 𝐻 ,  𝐾 〉 )  ∘  ( 1st  ‘ 〈 𝐹 ,  𝐺 〉 ) ) ,  ( 𝑥  ∈  𝐵 ,  𝑦  ∈  𝐵  ↦  ( ( ( ( 1st  ‘ 〈 𝐹 ,  𝐺 〉 ) ‘ 𝑥 ) ( 2nd  ‘ 〈 𝐻 ,  𝐾 〉 ) ( ( 1st  ‘ 〈 𝐹 ,  𝐺 〉 ) ‘ 𝑦 ) )  ∘  ( 𝑥 ( 2nd  ‘ 〈 𝐹 ,  𝐺 〉 ) 𝑦 ) ) ) 〉  =  〈 ( 𝐻  ∘  𝐹 ) ,  ( 𝑥  ∈  𝐵 ,  𝑦  ∈  𝐵  ↦  ( ( ( 𝐹 ‘ 𝑥 ) 𝐾 ( 𝐹 ‘ 𝑦 ) )  ∘  ( 𝑥 𝐺 𝑦 ) ) ) 〉 )  | 
						
						
							| 34 | 
							
								8 33
							 | 
							eqtrd | 
							⊢ ( 𝜑  →  ( 〈 𝐻 ,  𝐾 〉  ∘func  〈 𝐹 ,  𝐺 〉 )  =  〈 ( 𝐻  ∘  𝐹 ) ,  ( 𝑥  ∈  𝐵 ,  𝑦  ∈  𝐵  ↦  ( ( ( 𝐹 ‘ 𝑥 ) 𝐾 ( 𝐹 ‘ 𝑦 ) )  ∘  ( 𝑥 𝐺 𝑦 ) ) ) 〉 )  |