| Step | Hyp | Ref | Expression | 
						
							| 1 |  | pmtrdifel.t |  | 
						
							| 2 |  | pmtrdifel.r |  | 
						
							| 3 |  | pmtrdifel.0 |  | 
						
							| 4 |  | eqid |  | 
						
							| 5 | 4 1 | pmtrfb |  | 
						
							| 6 |  | difsnexi |  | 
						
							| 7 |  | f1of |  | 
						
							| 8 |  | fdm |  | 
						
							| 9 |  | difssd |  | 
						
							| 10 |  | dmss |  | 
						
							| 11 | 9 10 | syl |  | 
						
							| 12 |  | difssd |  | 
						
							| 13 |  | sseq1 |  | 
						
							| 14 | 12 13 | mpbird |  | 
						
							| 15 | 11 14 | sstrd |  | 
						
							| 16 | 7 8 15 | 3syl |  | 
						
							| 17 |  | id |  | 
						
							| 18 |  | eqid |  | 
						
							| 19 | 18 2 | pmtrrn |  | 
						
							| 20 | 3 19 | eqeltrid |  | 
						
							| 21 | 6 16 17 20 | syl3an |  | 
						
							| 22 | 5 21 | sylbi |  |