| Step | Hyp | Ref | Expression | 
						
							| 1 |  | sumdmdi.1 |  | 
						
							| 2 |  | sumdmdi.2 |  | 
						
							| 3 |  | dmdbr3 |  | 
						
							| 4 | 1 2 3 | mp2an |  | 
						
							| 5 |  | chabs2 |  | 
						
							| 6 | 2 5 | mpan2 |  | 
						
							| 7 | 6 | ineq2d |  | 
						
							| 8 |  | incom |  | 
						
							| 9 |  | inass |  | 
						
							| 10 |  | incom |  | 
						
							| 11 | 8 9 10 | 3eqtri |  | 
						
							| 12 | 7 11 | eqtr3di |  | 
						
							| 13 | 12 | adantr |  | 
						
							| 14 |  | ineq1 |  | 
						
							| 15 | 14 | adantl |  | 
						
							| 16 | 13 15 | eqtr4d |  | 
						
							| 17 | 16 | ralimiaa |  | 
						
							| 18 | 4 17 | sylbi |  | 
						
							| 19 |  | atelch |  | 
						
							| 20 | 19 | imim1i |  | 
						
							| 21 | 20 | ralimi2 |  | 
						
							| 22 | 18 21 | syl |  | 
						
							| 23 |  | inss1 |  | 
						
							| 24 |  | sseq1 |  | 
						
							| 25 | 23 24 | mpbiri |  | 
						
							| 26 |  | incom |  | 
						
							| 27 |  | dfss2 |  | 
						
							| 28 | 27 | biimpi |  | 
						
							| 29 | 26 28 | eqtrid |  | 
						
							| 30 | 29 | sseq1d |  | 
						
							| 31 | 25 30 | syl5ibcom |  | 
						
							| 32 | 31 | ralimi |  | 
						
							| 33 | 1 2 | dmdbr5ati |  | 
						
							| 34 | 32 33 | sylibr |  | 
						
							| 35 | 22 34 | impbii |  |