| Step | 
						Hyp | 
						Ref | 
						Expression | 
					
						
							| 1 | 
							
								
							 | 
							bnj1040.1 | 
							⊢ ( 𝜑′  ↔  [ 𝑗  /  𝑖 ] 𝜑 )  | 
						
						
							| 2 | 
							
								
							 | 
							bnj1040.2 | 
							⊢ ( 𝜓′  ↔  [ 𝑗  /  𝑖 ] 𝜓 )  | 
						
						
							| 3 | 
							
								
							 | 
							bnj1040.3 | 
							⊢ ( 𝜒  ↔  ( 𝑛  ∈  𝐷  ∧  𝑓  Fn  𝑛  ∧  𝜑  ∧  𝜓 ) )  | 
						
						
							| 4 | 
							
								
							 | 
							bnj1040.4 | 
							⊢ ( 𝜒′  ↔  [ 𝑗  /  𝑖 ] 𝜒 )  | 
						
						
							| 5 | 
							
								3
							 | 
							sbcbii | 
							⊢ ( [ 𝑗  /  𝑖 ] 𝜒  ↔  [ 𝑗  /  𝑖 ] ( 𝑛  ∈  𝐷  ∧  𝑓  Fn  𝑛  ∧  𝜑  ∧  𝜓 ) )  | 
						
						
							| 6 | 
							
								
							 | 
							df-bnj17 | 
							⊢ ( ( [ 𝑗  /  𝑖 ] 𝑛  ∈  𝐷  ∧  [ 𝑗  /  𝑖 ] 𝑓  Fn  𝑛  ∧  [ 𝑗  /  𝑖 ] 𝜑  ∧  [ 𝑗  /  𝑖 ] 𝜓 )  ↔  ( ( [ 𝑗  /  𝑖 ] 𝑛  ∈  𝐷  ∧  [ 𝑗  /  𝑖 ] 𝑓  Fn  𝑛  ∧  [ 𝑗  /  𝑖 ] 𝜑 )  ∧  [ 𝑗  /  𝑖 ] 𝜓 ) )  | 
						
						
							| 7 | 
							
								
							 | 
							vex | 
							⊢ 𝑗  ∈  V  | 
						
						
							| 8 | 
							
								7
							 | 
							bnj525 | 
							⊢ ( [ 𝑗  /  𝑖 ] 𝑛  ∈  𝐷  ↔  𝑛  ∈  𝐷 )  | 
						
						
							| 9 | 
							
								8
							 | 
							bicomi | 
							⊢ ( 𝑛  ∈  𝐷  ↔  [ 𝑗  /  𝑖 ] 𝑛  ∈  𝐷 )  | 
						
						
							| 10 | 
							
								7
							 | 
							bnj525 | 
							⊢ ( [ 𝑗  /  𝑖 ] 𝑓  Fn  𝑛  ↔  𝑓  Fn  𝑛 )  | 
						
						
							| 11 | 
							
								10
							 | 
							bicomi | 
							⊢ ( 𝑓  Fn  𝑛  ↔  [ 𝑗  /  𝑖 ] 𝑓  Fn  𝑛 )  | 
						
						
							| 12 | 
							
								9 11 1 2
							 | 
							bnj887 | 
							⊢ ( ( 𝑛  ∈  𝐷  ∧  𝑓  Fn  𝑛  ∧  𝜑′  ∧  𝜓′ )  ↔  ( [ 𝑗  /  𝑖 ] 𝑛  ∈  𝐷  ∧  [ 𝑗  /  𝑖 ] 𝑓  Fn  𝑛  ∧  [ 𝑗  /  𝑖 ] 𝜑  ∧  [ 𝑗  /  𝑖 ] 𝜓 ) )  | 
						
						
							| 13 | 
							
								
							 | 
							df-bnj17 | 
							⊢ ( ( 𝑛  ∈  𝐷  ∧  𝑓  Fn  𝑛  ∧  𝜑  ∧  𝜓 )  ↔  ( ( 𝑛  ∈  𝐷  ∧  𝑓  Fn  𝑛  ∧  𝜑 )  ∧  𝜓 ) )  | 
						
						
							| 14 | 
							
								13
							 | 
							sbcbii | 
							⊢ ( [ 𝑗  /  𝑖 ] ( 𝑛  ∈  𝐷  ∧  𝑓  Fn  𝑛  ∧  𝜑  ∧  𝜓 )  ↔  [ 𝑗  /  𝑖 ] ( ( 𝑛  ∈  𝐷  ∧  𝑓  Fn  𝑛  ∧  𝜑 )  ∧  𝜓 ) )  | 
						
						
							| 15 | 
							
								
							 | 
							sbcan | 
							⊢ ( [ 𝑗  /  𝑖 ] ( ( 𝑛  ∈  𝐷  ∧  𝑓  Fn  𝑛  ∧  𝜑 )  ∧  𝜓 )  ↔  ( [ 𝑗  /  𝑖 ] ( 𝑛  ∈  𝐷  ∧  𝑓  Fn  𝑛  ∧  𝜑 )  ∧  [ 𝑗  /  𝑖 ] 𝜓 ) )  | 
						
						
							| 16 | 
							
								
							 | 
							sbc3an | 
							⊢ ( [ 𝑗  /  𝑖 ] ( 𝑛  ∈  𝐷  ∧  𝑓  Fn  𝑛  ∧  𝜑 )  ↔  ( [ 𝑗  /  𝑖 ] 𝑛  ∈  𝐷  ∧  [ 𝑗  /  𝑖 ] 𝑓  Fn  𝑛  ∧  [ 𝑗  /  𝑖 ] 𝜑 ) )  | 
						
						
							| 17 | 
							
								16
							 | 
							anbi1i | 
							⊢ ( ( [ 𝑗  /  𝑖 ] ( 𝑛  ∈  𝐷  ∧  𝑓  Fn  𝑛  ∧  𝜑 )  ∧  [ 𝑗  /  𝑖 ] 𝜓 )  ↔  ( ( [ 𝑗  /  𝑖 ] 𝑛  ∈  𝐷  ∧  [ 𝑗  /  𝑖 ] 𝑓  Fn  𝑛  ∧  [ 𝑗  /  𝑖 ] 𝜑 )  ∧  [ 𝑗  /  𝑖 ] 𝜓 ) )  | 
						
						
							| 18 | 
							
								14 15 17
							 | 
							3bitri | 
							⊢ ( [ 𝑗  /  𝑖 ] ( 𝑛  ∈  𝐷  ∧  𝑓  Fn  𝑛  ∧  𝜑  ∧  𝜓 )  ↔  ( ( [ 𝑗  /  𝑖 ] 𝑛  ∈  𝐷  ∧  [ 𝑗  /  𝑖 ] 𝑓  Fn  𝑛  ∧  [ 𝑗  /  𝑖 ] 𝜑 )  ∧  [ 𝑗  /  𝑖 ] 𝜓 ) )  | 
						
						
							| 19 | 
							
								6 12 18
							 | 
							3bitr4ri | 
							⊢ ( [ 𝑗  /  𝑖 ] ( 𝑛  ∈  𝐷  ∧  𝑓  Fn  𝑛  ∧  𝜑  ∧  𝜓 )  ↔  ( 𝑛  ∈  𝐷  ∧  𝑓  Fn  𝑛  ∧  𝜑′  ∧  𝜓′ ) )  | 
						
						
							| 20 | 
							
								4 5 19
							 | 
							3bitri | 
							⊢ ( 𝜒′  ↔  ( 𝑛  ∈  𝐷  ∧  𝑓  Fn  𝑛  ∧  𝜑′  ∧  𝜓′ ) )  |