| 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 ) ) ) |