| Step | Hyp | Ref | Expression | 
						
							| 1 |  | cdlemg12.l |  | 
						
							| 2 |  | cdlemg12.j |  | 
						
							| 3 |  | cdlemg12.m |  | 
						
							| 4 |  | cdlemg12.a |  | 
						
							| 5 |  | cdlemg12.h |  | 
						
							| 6 |  | cdlemg12.t |  | 
						
							| 7 |  | cdlemg12b.r |  | 
						
							| 8 |  | simp3r |  | 
						
							| 9 |  | simpl1l |  | 
						
							| 10 |  | simpl21 |  | 
						
							| 11 |  | simpl1 |  | 
						
							| 12 |  | simpl23 |  | 
						
							| 13 |  | simpl22 |  | 
						
							| 14 | 1 4 5 6 | ltrnat |  | 
						
							| 15 | 11 12 13 14 | syl3anc |  | 
						
							| 16 | 1 4 5 6 | ltrnat |  | 
						
							| 17 | 11 12 10 16 | syl3anc |  | 
						
							| 18 |  | simpl3l |  | 
						
							| 19 | 4 5 6 | ltrn11at |  | 
						
							| 20 | 11 12 10 13 18 19 | syl113anc |  | 
						
							| 21 | 20 | necomd |  | 
						
							| 22 |  | simpr |  | 
						
							| 23 | 2 4 | hlatexch4 |  | 
						
							| 24 | 9 10 15 13 17 18 21 22 23 | syl323anc |  | 
						
							| 25 | 24 | eqcomd |  | 
						
							| 26 | 25 | ex |  | 
						
							| 27 | 26 | necon3d |  | 
						
							| 28 | 8 27 | mpd |  |