| Step | 
						Hyp | 
						Ref | 
						Expression | 
					
						
							| 1 | 
							
								
							 | 
							ovmpos.3 | 
							⊢ 𝐹  =  ( 𝑥  ∈  𝐶 ,  𝑦  ∈  𝐷  ↦  𝑅 )  | 
						
						
							| 2 | 
							
								
							 | 
							elex | 
							⊢ ( ⦋ 𝐴  /  𝑥 ⦌ ⦋ 𝐵  /  𝑦 ⦌ 𝑅  ∈  𝑉  →  ⦋ 𝐴  /  𝑥 ⦌ ⦋ 𝐵  /  𝑦 ⦌ 𝑅  ∈  V )  | 
						
						
							| 3 | 
							
								
							 | 
							nfcv | 
							⊢ Ⅎ 𝑥 𝐴  | 
						
						
							| 4 | 
							
								
							 | 
							nfcv | 
							⊢ Ⅎ 𝑦 𝐴  | 
						
						
							| 5 | 
							
								
							 | 
							nfcv | 
							⊢ Ⅎ 𝑦 𝐵  | 
						
						
							| 6 | 
							
								
							 | 
							nfcsb1v | 
							⊢ Ⅎ 𝑥 ⦋ 𝐴  /  𝑥 ⦌ 𝑅  | 
						
						
							| 7 | 
							
								6
							 | 
							nfel1 | 
							⊢ Ⅎ 𝑥 ⦋ 𝐴  /  𝑥 ⦌ 𝑅  ∈  V  | 
						
						
							| 8 | 
							
								
							 | 
							nfmpo1 | 
							⊢ Ⅎ 𝑥 ( 𝑥  ∈  𝐶 ,  𝑦  ∈  𝐷  ↦  𝑅 )  | 
						
						
							| 9 | 
							
								1 8
							 | 
							nfcxfr | 
							⊢ Ⅎ 𝑥 𝐹  | 
						
						
							| 10 | 
							
								
							 | 
							nfcv | 
							⊢ Ⅎ 𝑥 𝑦  | 
						
						
							| 11 | 
							
								3 9 10
							 | 
							nfov | 
							⊢ Ⅎ 𝑥 ( 𝐴 𝐹 𝑦 )  | 
						
						
							| 12 | 
							
								11 6
							 | 
							nfeq | 
							⊢ Ⅎ 𝑥 ( 𝐴 𝐹 𝑦 )  =  ⦋ 𝐴  /  𝑥 ⦌ 𝑅  | 
						
						
							| 13 | 
							
								7 12
							 | 
							nfim | 
							⊢ Ⅎ 𝑥 ( ⦋ 𝐴  /  𝑥 ⦌ 𝑅  ∈  V  →  ( 𝐴 𝐹 𝑦 )  =  ⦋ 𝐴  /  𝑥 ⦌ 𝑅 )  | 
						
						
							| 14 | 
							
								
							 | 
							nfcsb1v | 
							⊢ Ⅎ 𝑦 ⦋ 𝐵  /  𝑦 ⦌ ⦋ 𝐴  /  𝑥 ⦌ 𝑅  | 
						
						
							| 15 | 
							
								14
							 | 
							nfel1 | 
							⊢ Ⅎ 𝑦 ⦋ 𝐵  /  𝑦 ⦌ ⦋ 𝐴  /  𝑥 ⦌ 𝑅  ∈  V  | 
						
						
							| 16 | 
							
								
							 | 
							nfmpo2 | 
							⊢ Ⅎ 𝑦 ( 𝑥  ∈  𝐶 ,  𝑦  ∈  𝐷  ↦  𝑅 )  | 
						
						
							| 17 | 
							
								1 16
							 | 
							nfcxfr | 
							⊢ Ⅎ 𝑦 𝐹  | 
						
						
							| 18 | 
							
								4 17 5
							 | 
							nfov | 
							⊢ Ⅎ 𝑦 ( 𝐴 𝐹 𝐵 )  | 
						
						
							| 19 | 
							
								18 14
							 | 
							nfeq | 
							⊢ Ⅎ 𝑦 ( 𝐴 𝐹 𝐵 )  =  ⦋ 𝐵  /  𝑦 ⦌ ⦋ 𝐴  /  𝑥 ⦌ 𝑅  | 
						
						
							| 20 | 
							
								15 19
							 | 
							nfim | 
							⊢ Ⅎ 𝑦 ( ⦋ 𝐵  /  𝑦 ⦌ ⦋ 𝐴  /  𝑥 ⦌ 𝑅  ∈  V  →  ( 𝐴 𝐹 𝐵 )  =  ⦋ 𝐵  /  𝑦 ⦌ ⦋ 𝐴  /  𝑥 ⦌ 𝑅 )  | 
						
						
							| 21 | 
							
								
							 | 
							csbeq1a | 
							⊢ ( 𝑥  =  𝐴  →  𝑅  =  ⦋ 𝐴  /  𝑥 ⦌ 𝑅 )  | 
						
						
							| 22 | 
							
								21
							 | 
							eleq1d | 
							⊢ ( 𝑥  =  𝐴  →  ( 𝑅  ∈  V  ↔  ⦋ 𝐴  /  𝑥 ⦌ 𝑅  ∈  V ) )  | 
						
						
							| 23 | 
							
								
							 | 
							oveq1 | 
							⊢ ( 𝑥  =  𝐴  →  ( 𝑥 𝐹 𝑦 )  =  ( 𝐴 𝐹 𝑦 ) )  | 
						
						
							| 24 | 
							
								23 21
							 | 
							eqeq12d | 
							⊢ ( 𝑥  =  𝐴  →  ( ( 𝑥 𝐹 𝑦 )  =  𝑅  ↔  ( 𝐴 𝐹 𝑦 )  =  ⦋ 𝐴  /  𝑥 ⦌ 𝑅 ) )  | 
						
						
							| 25 | 
							
								22 24
							 | 
							imbi12d | 
							⊢ ( 𝑥  =  𝐴  →  ( ( 𝑅  ∈  V  →  ( 𝑥 𝐹 𝑦 )  =  𝑅 )  ↔  ( ⦋ 𝐴  /  𝑥 ⦌ 𝑅  ∈  V  →  ( 𝐴 𝐹 𝑦 )  =  ⦋ 𝐴  /  𝑥 ⦌ 𝑅 ) ) )  | 
						
						
							| 26 | 
							
								
							 | 
							csbeq1a | 
							⊢ ( 𝑦  =  𝐵  →  ⦋ 𝐴  /  𝑥 ⦌ 𝑅  =  ⦋ 𝐵  /  𝑦 ⦌ ⦋ 𝐴  /  𝑥 ⦌ 𝑅 )  | 
						
						
							| 27 | 
							
								26
							 | 
							eleq1d | 
							⊢ ( 𝑦  =  𝐵  →  ( ⦋ 𝐴  /  𝑥 ⦌ 𝑅  ∈  V  ↔  ⦋ 𝐵  /  𝑦 ⦌ ⦋ 𝐴  /  𝑥 ⦌ 𝑅  ∈  V ) )  | 
						
						
							| 28 | 
							
								
							 | 
							oveq2 | 
							⊢ ( 𝑦  =  𝐵  →  ( 𝐴 𝐹 𝑦 )  =  ( 𝐴 𝐹 𝐵 ) )  | 
						
						
							| 29 | 
							
								28 26
							 | 
							eqeq12d | 
							⊢ ( 𝑦  =  𝐵  →  ( ( 𝐴 𝐹 𝑦 )  =  ⦋ 𝐴  /  𝑥 ⦌ 𝑅  ↔  ( 𝐴 𝐹 𝐵 )  =  ⦋ 𝐵  /  𝑦 ⦌ ⦋ 𝐴  /  𝑥 ⦌ 𝑅 ) )  | 
						
						
							| 30 | 
							
								27 29
							 | 
							imbi12d | 
							⊢ ( 𝑦  =  𝐵  →  ( ( ⦋ 𝐴  /  𝑥 ⦌ 𝑅  ∈  V  →  ( 𝐴 𝐹 𝑦 )  =  ⦋ 𝐴  /  𝑥 ⦌ 𝑅 )  ↔  ( ⦋ 𝐵  /  𝑦 ⦌ ⦋ 𝐴  /  𝑥 ⦌ 𝑅  ∈  V  →  ( 𝐴 𝐹 𝐵 )  =  ⦋ 𝐵  /  𝑦 ⦌ ⦋ 𝐴  /  𝑥 ⦌ 𝑅 ) ) )  | 
						
						
							| 31 | 
							
								1
							 | 
							ovmpt4g | 
							⊢ ( ( 𝑥  ∈  𝐶  ∧  𝑦  ∈  𝐷  ∧  𝑅  ∈  V )  →  ( 𝑥 𝐹 𝑦 )  =  𝑅 )  | 
						
						
							| 32 | 
							
								31
							 | 
							3expia | 
							⊢ ( ( 𝑥  ∈  𝐶  ∧  𝑦  ∈  𝐷 )  →  ( 𝑅  ∈  V  →  ( 𝑥 𝐹 𝑦 )  =  𝑅 ) )  | 
						
						
							| 33 | 
							
								3 4 5 13 20 25 30 32
							 | 
							vtocl2gaf | 
							⊢ ( ( 𝐴  ∈  𝐶  ∧  𝐵  ∈  𝐷 )  →  ( ⦋ 𝐵  /  𝑦 ⦌ ⦋ 𝐴  /  𝑥 ⦌ 𝑅  ∈  V  →  ( 𝐴 𝐹 𝐵 )  =  ⦋ 𝐵  /  𝑦 ⦌ ⦋ 𝐴  /  𝑥 ⦌ 𝑅 ) )  | 
						
						
							| 34 | 
							
								
							 | 
							csbcom | 
							⊢ ⦋ 𝐴  /  𝑥 ⦌ ⦋ 𝐵  /  𝑦 ⦌ 𝑅  =  ⦋ 𝐵  /  𝑦 ⦌ ⦋ 𝐴  /  𝑥 ⦌ 𝑅  | 
						
						
							| 35 | 
							
								34
							 | 
							eleq1i | 
							⊢ ( ⦋ 𝐴  /  𝑥 ⦌ ⦋ 𝐵  /  𝑦 ⦌ 𝑅  ∈  V  ↔  ⦋ 𝐵  /  𝑦 ⦌ ⦋ 𝐴  /  𝑥 ⦌ 𝑅  ∈  V )  | 
						
						
							| 36 | 
							
								34
							 | 
							eqeq2i | 
							⊢ ( ( 𝐴 𝐹 𝐵 )  =  ⦋ 𝐴  /  𝑥 ⦌ ⦋ 𝐵  /  𝑦 ⦌ 𝑅  ↔  ( 𝐴 𝐹 𝐵 )  =  ⦋ 𝐵  /  𝑦 ⦌ ⦋ 𝐴  /  𝑥 ⦌ 𝑅 )  | 
						
						
							| 37 | 
							
								33 35 36
							 | 
							3imtr4g | 
							⊢ ( ( 𝐴  ∈  𝐶  ∧  𝐵  ∈  𝐷 )  →  ( ⦋ 𝐴  /  𝑥 ⦌ ⦋ 𝐵  /  𝑦 ⦌ 𝑅  ∈  V  →  ( 𝐴 𝐹 𝐵 )  =  ⦋ 𝐴  /  𝑥 ⦌ ⦋ 𝐵  /  𝑦 ⦌ 𝑅 ) )  | 
						
						
							| 38 | 
							
								2 37
							 | 
							syl5 | 
							⊢ ( ( 𝐴  ∈  𝐶  ∧  𝐵  ∈  𝐷 )  →  ( ⦋ 𝐴  /  𝑥 ⦌ ⦋ 𝐵  /  𝑦 ⦌ 𝑅  ∈  𝑉  →  ( 𝐴 𝐹 𝐵 )  =  ⦋ 𝐴  /  𝑥 ⦌ ⦋ 𝐵  /  𝑦 ⦌ 𝑅 ) )  | 
						
						
							| 39 | 
							
								38
							 | 
							3impia | 
							⊢ ( ( 𝐴  ∈  𝐶  ∧  𝐵  ∈  𝐷  ∧  ⦋ 𝐴  /  𝑥 ⦌ ⦋ 𝐵  /  𝑦 ⦌ 𝑅  ∈  𝑉 )  →  ( 𝐴 𝐹 𝐵 )  =  ⦋ 𝐴  /  𝑥 ⦌ ⦋ 𝐵  /  𝑦 ⦌ 𝑅 )  |