| Step | Hyp | Ref | Expression | 
						
							| 1 |  | ercpbl.r | ⊢ ( 𝜑  →   ∼   Er  𝑉 ) | 
						
							| 2 |  | ercpbl.v | ⊢ ( 𝜑  →  𝑉  ∈  𝑊 ) | 
						
							| 3 |  | ercpbl.f | ⊢ 𝐹  =  ( 𝑥  ∈  𝑉  ↦  [ 𝑥 ]  ∼  ) | 
						
							| 4 |  | ercpbl.c | ⊢ ( ( 𝜑  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) )  →  ( 𝑎  +  𝑏 )  ∈  𝑉 ) | 
						
							| 5 |  | ercpbl.e | ⊢ ( 𝜑  →  ( ( 𝐴  ∼  𝐶  ∧  𝐵  ∼  𝐷 )  →  ( 𝐴  +  𝐵 )  ∼  ( 𝐶  +  𝐷 ) ) ) | 
						
							| 6 | 5 | 3ad2ant1 | ⊢ ( ( 𝜑  ∧  ( 𝐴  ∈  𝑉  ∧  𝐵  ∈  𝑉 )  ∧  ( 𝐶  ∈  𝑉  ∧  𝐷  ∈  𝑉 ) )  →  ( ( 𝐴  ∼  𝐶  ∧  𝐵  ∼  𝐷 )  →  ( 𝐴  +  𝐵 )  ∼  ( 𝐶  +  𝐷 ) ) ) | 
						
							| 7 | 1 | 3ad2ant1 | ⊢ ( ( 𝜑  ∧  ( 𝐴  ∈  𝑉  ∧  𝐵  ∈  𝑉 )  ∧  ( 𝐶  ∈  𝑉  ∧  𝐷  ∈  𝑉 ) )  →   ∼   Er  𝑉 ) | 
						
							| 8 | 2 | 3ad2ant1 | ⊢ ( ( 𝜑  ∧  ( 𝐴  ∈  𝑉  ∧  𝐵  ∈  𝑉 )  ∧  ( 𝐶  ∈  𝑉  ∧  𝐷  ∈  𝑉 ) )  →  𝑉  ∈  𝑊 ) | 
						
							| 9 |  | simp2l | ⊢ ( ( 𝜑  ∧  ( 𝐴  ∈  𝑉  ∧  𝐵  ∈  𝑉 )  ∧  ( 𝐶  ∈  𝑉  ∧  𝐷  ∈  𝑉 ) )  →  𝐴  ∈  𝑉 ) | 
						
							| 10 | 7 8 3 9 | ercpbllem | ⊢ ( ( 𝜑  ∧  ( 𝐴  ∈  𝑉  ∧  𝐵  ∈  𝑉 )  ∧  ( 𝐶  ∈  𝑉  ∧  𝐷  ∈  𝑉 ) )  →  ( ( 𝐹 ‘ 𝐴 )  =  ( 𝐹 ‘ 𝐶 )  ↔  𝐴  ∼  𝐶 ) ) | 
						
							| 11 |  | simp2r | ⊢ ( ( 𝜑  ∧  ( 𝐴  ∈  𝑉  ∧  𝐵  ∈  𝑉 )  ∧  ( 𝐶  ∈  𝑉  ∧  𝐷  ∈  𝑉 ) )  →  𝐵  ∈  𝑉 ) | 
						
							| 12 | 7 8 3 11 | ercpbllem | ⊢ ( ( 𝜑  ∧  ( 𝐴  ∈  𝑉  ∧  𝐵  ∈  𝑉 )  ∧  ( 𝐶  ∈  𝑉  ∧  𝐷  ∈  𝑉 ) )  →  ( ( 𝐹 ‘ 𝐵 )  =  ( 𝐹 ‘ 𝐷 )  ↔  𝐵  ∼  𝐷 ) ) | 
						
							| 13 | 10 12 | anbi12d | ⊢ ( ( 𝜑  ∧  ( 𝐴  ∈  𝑉  ∧  𝐵  ∈  𝑉 )  ∧  ( 𝐶  ∈  𝑉  ∧  𝐷  ∈  𝑉 ) )  →  ( ( ( 𝐹 ‘ 𝐴 )  =  ( 𝐹 ‘ 𝐶 )  ∧  ( 𝐹 ‘ 𝐵 )  =  ( 𝐹 ‘ 𝐷 ) )  ↔  ( 𝐴  ∼  𝐶  ∧  𝐵  ∼  𝐷 ) ) ) | 
						
							| 14 | 4 | caovclg | ⊢ ( ( 𝜑  ∧  ( 𝐴  ∈  𝑉  ∧  𝐵  ∈  𝑉 ) )  →  ( 𝐴  +  𝐵 )  ∈  𝑉 ) | 
						
							| 15 | 14 | 3adant3 | ⊢ ( ( 𝜑  ∧  ( 𝐴  ∈  𝑉  ∧  𝐵  ∈  𝑉 )  ∧  ( 𝐶  ∈  𝑉  ∧  𝐷  ∈  𝑉 ) )  →  ( 𝐴  +  𝐵 )  ∈  𝑉 ) | 
						
							| 16 | 7 8 3 15 | ercpbllem | ⊢ ( ( 𝜑  ∧  ( 𝐴  ∈  𝑉  ∧  𝐵  ∈  𝑉 )  ∧  ( 𝐶  ∈  𝑉  ∧  𝐷  ∈  𝑉 ) )  →  ( ( 𝐹 ‘ ( 𝐴  +  𝐵 ) )  =  ( 𝐹 ‘ ( 𝐶  +  𝐷 ) )  ↔  ( 𝐴  +  𝐵 )  ∼  ( 𝐶  +  𝐷 ) ) ) | 
						
							| 17 | 6 13 16 | 3imtr4d | ⊢ ( ( 𝜑  ∧  ( 𝐴  ∈  𝑉  ∧  𝐵  ∈  𝑉 )  ∧  ( 𝐶  ∈  𝑉  ∧  𝐷  ∈  𝑉 ) )  →  ( ( ( 𝐹 ‘ 𝐴 )  =  ( 𝐹 ‘ 𝐶 )  ∧  ( 𝐹 ‘ 𝐵 )  =  ( 𝐹 ‘ 𝐷 ) )  →  ( 𝐹 ‘ ( 𝐴  +  𝐵 ) )  =  ( 𝐹 ‘ ( 𝐶  +  𝐷 ) ) ) ) |