| Step | Hyp | Ref | Expression | 
						
							| 1 |  | dfon2 |  | 
						
							| 2 |  | eqabcb |  | 
						
							| 3 |  | vex |  | 
						
							| 4 | 3 | elrn |  | 
						
							| 5 |  | brin |  | 
						
							| 6 | 3 | brsset |  | 
						
							| 7 |  | brxp |  | 
						
							| 8 | 3 7 | mpbiran2 |  | 
						
							| 9 |  | vex |  | 
						
							| 10 | 9 | eltrans |  | 
						
							| 11 | 8 10 | bitri |  | 
						
							| 12 | 6 11 | anbi12i |  | 
						
							| 13 | 5 12 | bitri |  | 
						
							| 14 |  | ioran |  | 
						
							| 15 |  | brun |  | 
						
							| 16 | 3 | ideq |  | 
						
							| 17 |  | epel |  | 
						
							| 18 | 16 17 | orbi12i |  | 
						
							| 19 | 15 18 | bitri |  | 
						
							| 20 | 14 19 | xchnxbir |  | 
						
							| 21 | 13 20 | anbi12i |  | 
						
							| 22 |  | brdif |  | 
						
							| 23 |  | dfpss2 |  | 
						
							| 24 | 23 | anbi1i |  | 
						
							| 25 |  | an32 |  | 
						
							| 26 | 24 25 | bitri |  | 
						
							| 27 | 26 | anbi1i |  | 
						
							| 28 |  | anass |  | 
						
							| 29 | 27 28 | bitri |  | 
						
							| 30 | 21 22 29 | 3bitr4i |  | 
						
							| 31 | 30 | exbii |  | 
						
							| 32 |  | exanali |  | 
						
							| 33 | 31 32 | bitri |  | 
						
							| 34 | 4 33 | bitri |  | 
						
							| 35 | 34 | con2bii |  | 
						
							| 36 |  | eldif |  | 
						
							| 37 | 3 36 | mpbiran |  | 
						
							| 38 | 35 37 | bitr4i |  | 
						
							| 39 | 2 38 | mpgbir |  | 
						
							| 40 | 1 39 | eqtri |  |