| Step | 
						Hyp | 
						Ref | 
						Expression | 
					
						
							| 1 | 
							
								
							 | 
							caovord.1 | 
							⊢ 𝐴  ∈  V  | 
						
						
							| 2 | 
							
								
							 | 
							caovord.2 | 
							⊢ 𝐵  ∈  V  | 
						
						
							| 3 | 
							
								
							 | 
							caovord.3 | 
							⊢ ( 𝑧  ∈  𝑆  →  ( 𝑥 𝑅 𝑦  ↔  ( 𝑧 𝐹 𝑥 ) 𝑅 ( 𝑧 𝐹 𝑦 ) ) )  | 
						
						
							| 4 | 
							
								
							 | 
							oveq1 | 
							⊢ ( 𝑧  =  𝐶  →  ( 𝑧 𝐹 𝐴 )  =  ( 𝐶 𝐹 𝐴 ) )  | 
						
						
							| 5 | 
							
								
							 | 
							oveq1 | 
							⊢ ( 𝑧  =  𝐶  →  ( 𝑧 𝐹 𝐵 )  =  ( 𝐶 𝐹 𝐵 ) )  | 
						
						
							| 6 | 
							
								4 5
							 | 
							breq12d | 
							⊢ ( 𝑧  =  𝐶  →  ( ( 𝑧 𝐹 𝐴 ) 𝑅 ( 𝑧 𝐹 𝐵 )  ↔  ( 𝐶 𝐹 𝐴 ) 𝑅 ( 𝐶 𝐹 𝐵 ) ) )  | 
						
						
							| 7 | 
							
								6
							 | 
							bibi2d | 
							⊢ ( 𝑧  =  𝐶  →  ( ( 𝐴 𝑅 𝐵  ↔  ( 𝑧 𝐹 𝐴 ) 𝑅 ( 𝑧 𝐹 𝐵 ) )  ↔  ( 𝐴 𝑅 𝐵  ↔  ( 𝐶 𝐹 𝐴 ) 𝑅 ( 𝐶 𝐹 𝐵 ) ) ) )  | 
						
						
							| 8 | 
							
								
							 | 
							breq1 | 
							⊢ ( 𝑥  =  𝐴  →  ( 𝑥 𝑅 𝑦  ↔  𝐴 𝑅 𝑦 ) )  | 
						
						
							| 9 | 
							
								
							 | 
							oveq2 | 
							⊢ ( 𝑥  =  𝐴  →  ( 𝑧 𝐹 𝑥 )  =  ( 𝑧 𝐹 𝐴 ) )  | 
						
						
							| 10 | 
							
								9
							 | 
							breq1d | 
							⊢ ( 𝑥  =  𝐴  →  ( ( 𝑧 𝐹 𝑥 ) 𝑅 ( 𝑧 𝐹 𝑦 )  ↔  ( 𝑧 𝐹 𝐴 ) 𝑅 ( 𝑧 𝐹 𝑦 ) ) )  | 
						
						
							| 11 | 
							
								8 10
							 | 
							bibi12d | 
							⊢ ( 𝑥  =  𝐴  →  ( ( 𝑥 𝑅 𝑦  ↔  ( 𝑧 𝐹 𝑥 ) 𝑅 ( 𝑧 𝐹 𝑦 ) )  ↔  ( 𝐴 𝑅 𝑦  ↔  ( 𝑧 𝐹 𝐴 ) 𝑅 ( 𝑧 𝐹 𝑦 ) ) ) )  | 
						
						
							| 12 | 
							
								
							 | 
							breq2 | 
							⊢ ( 𝑦  =  𝐵  →  ( 𝐴 𝑅 𝑦  ↔  𝐴 𝑅 𝐵 ) )  | 
						
						
							| 13 | 
							
								
							 | 
							oveq2 | 
							⊢ ( 𝑦  =  𝐵  →  ( 𝑧 𝐹 𝑦 )  =  ( 𝑧 𝐹 𝐵 ) )  | 
						
						
							| 14 | 
							
								13
							 | 
							breq2d | 
							⊢ ( 𝑦  =  𝐵  →  ( ( 𝑧 𝐹 𝐴 ) 𝑅 ( 𝑧 𝐹 𝑦 )  ↔  ( 𝑧 𝐹 𝐴 ) 𝑅 ( 𝑧 𝐹 𝐵 ) ) )  | 
						
						
							| 15 | 
							
								12 14
							 | 
							bibi12d | 
							⊢ ( 𝑦  =  𝐵  →  ( ( 𝐴 𝑅 𝑦  ↔  ( 𝑧 𝐹 𝐴 ) 𝑅 ( 𝑧 𝐹 𝑦 ) )  ↔  ( 𝐴 𝑅 𝐵  ↔  ( 𝑧 𝐹 𝐴 ) 𝑅 ( 𝑧 𝐹 𝐵 ) ) ) )  | 
						
						
							| 16 | 
							
								11 15
							 | 
							sylan9bb | 
							⊢ ( ( 𝑥  =  𝐴  ∧  𝑦  =  𝐵 )  →  ( ( 𝑥 𝑅 𝑦  ↔  ( 𝑧 𝐹 𝑥 ) 𝑅 ( 𝑧 𝐹 𝑦 ) )  ↔  ( 𝐴 𝑅 𝐵  ↔  ( 𝑧 𝐹 𝐴 ) 𝑅 ( 𝑧 𝐹 𝐵 ) ) ) )  | 
						
						
							| 17 | 
							
								16
							 | 
							imbi2d | 
							⊢ ( ( 𝑥  =  𝐴  ∧  𝑦  =  𝐵 )  →  ( ( 𝑧  ∈  𝑆  →  ( 𝑥 𝑅 𝑦  ↔  ( 𝑧 𝐹 𝑥 ) 𝑅 ( 𝑧 𝐹 𝑦 ) ) )  ↔  ( 𝑧  ∈  𝑆  →  ( 𝐴 𝑅 𝐵  ↔  ( 𝑧 𝐹 𝐴 ) 𝑅 ( 𝑧 𝐹 𝐵 ) ) ) ) )  | 
						
						
							| 18 | 
							
								1 2 17 3
							 | 
							vtocl2 | 
							⊢ ( 𝑧  ∈  𝑆  →  ( 𝐴 𝑅 𝐵  ↔  ( 𝑧 𝐹 𝐴 ) 𝑅 ( 𝑧 𝐹 𝐵 ) ) )  | 
						
						
							| 19 | 
							
								7 18
							 | 
							vtoclga | 
							⊢ ( 𝐶  ∈  𝑆  →  ( 𝐴 𝑅 𝐵  ↔  ( 𝐶 𝐹 𝐴 ) 𝑅 ( 𝐶 𝐹 𝐵 ) ) )  |