| Step | Hyp | Ref | Expression | 
						
							| 1 |  | ttukeylem.1 |  | 
						
							| 2 |  | ttukeylem.2 |  | 
						
							| 3 |  | ttukeylem.3 |  | 
						
							| 4 |  | elex |  | 
						
							| 5 | 4 | a1i |  | 
						
							| 6 |  | id |  | 
						
							| 7 |  | ssun1 |  | 
						
							| 8 |  | undif1 |  | 
						
							| 9 | 7 8 | sseqtrri |  | 
						
							| 10 |  | fvex |  | 
						
							| 11 |  | f1ofo |  | 
						
							| 12 | 1 11 | syl |  | 
						
							| 13 |  | focdmex |  | 
						
							| 14 | 10 12 13 | mpsyl |  | 
						
							| 15 |  | unexg |  | 
						
							| 16 | 14 2 15 | syl2anc |  | 
						
							| 17 |  | ssexg |  | 
						
							| 18 | 9 16 17 | sylancr |  | 
						
							| 19 |  | uniexb |  | 
						
							| 20 | 18 19 | sylibr |  | 
						
							| 21 |  | ssexg |  | 
						
							| 22 | 6 20 21 | syl2anr |  | 
						
							| 23 |  | infpwfidom |  | 
						
							| 24 |  | reldom |  | 
						
							| 25 | 24 | brrelex1i |  | 
						
							| 26 | 22 23 25 | 3syl |  | 
						
							| 27 | 26 | ex |  | 
						
							| 28 |  | eleq1 |  | 
						
							| 29 |  | pweq |  | 
						
							| 30 | 29 | ineq1d |  | 
						
							| 31 | 30 | sseq1d |  | 
						
							| 32 | 28 31 | bibi12d |  | 
						
							| 33 | 32 | spcgv |  | 
						
							| 34 | 3 33 | syl5com |  | 
						
							| 35 | 5 27 34 | pm5.21ndd |  |