| Step | Hyp | Ref | Expression | 
						
							| 1 |  | difeq2 |  | 
						
							| 2 | 1 | eleq1d |  | 
						
							| 3 | 2 | elrab |  | 
						
							| 4 |  | difeq2 |  | 
						
							| 5 | 4 | eleq1d |  | 
						
							| 6 | 5 | elrab |  | 
						
							| 7 |  | an4 |  | 
						
							| 8 | 7 | biimpi |  | 
						
							| 9 | 3 6 8 | syl2anb |  | 
						
							| 10 |  | sorpssi |  | 
						
							| 11 | 10 | expcom |  | 
						
							| 12 |  | velpw |  | 
						
							| 13 |  | dfss4 |  | 
						
							| 14 | 12 13 | bitri |  | 
						
							| 15 |  | velpw |  | 
						
							| 16 |  | dfss4 |  | 
						
							| 17 | 15 16 | bitri |  | 
						
							| 18 |  | sscon |  | 
						
							| 19 |  | sseq12 |  | 
						
							| 20 | 18 19 | imbitrid |  | 
						
							| 21 |  | sscon |  | 
						
							| 22 |  | sseq12 |  | 
						
							| 23 | 22 | ancoms |  | 
						
							| 24 | 21 23 | imbitrid |  | 
						
							| 25 | 20 24 | orim12d |  | 
						
							| 26 | 14 17 25 | syl2anb |  | 
						
							| 27 | 26 | com12 |  | 
						
							| 28 | 27 | orcoms |  | 
						
							| 29 | 11 28 | syl6 |  | 
						
							| 30 | 29 | com3l |  | 
						
							| 31 | 30 | impd |  | 
						
							| 32 | 9 31 | syl5 |  | 
						
							| 33 | 32 | ralrimivv |  | 
						
							| 34 |  | sorpss |  | 
						
							| 35 | 33 34 | sylibr |  |