| Step | Hyp | Ref | Expression | 
						
							| 1 |  | relsdom |  | 
						
							| 2 | 1 | brrelex2i |  | 
						
							| 3 | 2 | adantr |  | 
						
							| 4 |  | 1onn |  | 
						
							| 5 |  | xpsneng |  | 
						
							| 6 | 3 4 5 | sylancl |  | 
						
							| 7 | 6 | ensymd |  | 
						
							| 8 |  | endom |  | 
						
							| 9 | 7 8 | syl |  | 
						
							| 10 |  | simpr |  | 
						
							| 11 |  | 0ex |  | 
						
							| 12 |  | xpsneng |  | 
						
							| 13 | 3 11 12 | sylancl |  | 
						
							| 14 | 13 | ensymd |  | 
						
							| 15 |  | domentr |  | 
						
							| 16 | 10 14 15 | syl2anc |  | 
						
							| 17 |  | 1n0 |  | 
						
							| 18 |  | xpsndisj |  | 
						
							| 19 | 17 18 | mp1i |  | 
						
							| 20 |  | undom |  | 
						
							| 21 | 9 16 19 20 | syl21anc |  | 
						
							| 22 |  | sdomentr |  | 
						
							| 23 | 7 22 | syldan |  | 
						
							| 24 |  | sdomentr |  | 
						
							| 25 | 14 24 | syldan |  | 
						
							| 26 |  | unxpdom |  | 
						
							| 27 | 23 25 26 | syl2anc |  | 
						
							| 28 |  | xpen |  | 
						
							| 29 | 6 13 28 | syl2anc |  | 
						
							| 30 |  | domentr |  | 
						
							| 31 | 27 29 30 | syl2anc |  | 
						
							| 32 |  | domtr |  | 
						
							| 33 | 21 31 32 | syl2anc |  |