| Step | Hyp | Ref | Expression | 
						
							| 1 |  | psrgrp.s |  | 
						
							| 2 |  | psrgrp.i |  | 
						
							| 3 |  | psrgrp.r |  | 
						
							| 4 |  | psrneg.d |  | 
						
							| 5 |  | psrneg.i |  | 
						
							| 6 |  | psrneg.b |  | 
						
							| 7 |  | psrneg.m |  | 
						
							| 8 |  | psrneg.x |  | 
						
							| 9 |  | eqid |  | 
						
							| 10 |  | eqid |  | 
						
							| 11 | 1 2 3 4 5 6 8 9 10 | psrlinv |  | 
						
							| 12 |  | eqid |  | 
						
							| 13 | 1 2 3 4 9 12 | psr0 |  | 
						
							| 14 | 11 13 | eqtr4d |  | 
						
							| 15 | 1 2 3 | psrgrp |  | 
						
							| 16 | 1 2 3 4 5 6 8 | psrnegcl |  | 
						
							| 17 | 6 10 12 7 | grpinvid2 |  | 
						
							| 18 | 15 8 16 17 | syl3anc |  | 
						
							| 19 | 14 18 | mpbird |  |