| Step | Hyp | Ref | Expression | 
						
							| 1 |  | iccshftr.1 |  | 
						
							| 2 |  | iccshftr.2 |  | 
						
							| 3 |  | simpl |  | 
						
							| 4 |  | readdcl |  | 
						
							| 5 | 3 4 | 2thd |  | 
						
							| 6 | 5 | adantl |  | 
						
							| 7 |  | leadd1 |  | 
						
							| 8 | 7 | 3expb |  | 
						
							| 9 | 8 | adantlr |  | 
						
							| 10 | 1 | breq1i |  | 
						
							| 11 | 9 10 | bitrdi |  | 
						
							| 12 |  | leadd1 |  | 
						
							| 13 | 12 | 3expb |  | 
						
							| 14 | 13 | an12s |  | 
						
							| 15 | 14 | adantll |  | 
						
							| 16 | 2 | breq2i |  | 
						
							| 17 | 15 16 | bitrdi |  | 
						
							| 18 | 6 11 17 | 3anbi123d |  | 
						
							| 19 |  | elicc2 |  | 
						
							| 20 | 19 | adantr |  | 
						
							| 21 |  | readdcl |  | 
						
							| 22 | 1 21 | eqeltrrid |  | 
						
							| 23 |  | readdcl |  | 
						
							| 24 | 2 23 | eqeltrrid |  | 
						
							| 25 |  | elicc2 |  | 
						
							| 26 | 22 24 25 | syl2an |  | 
						
							| 27 | 26 | anandirs |  | 
						
							| 28 | 27 | adantrl |  | 
						
							| 29 | 18 20 28 | 3bitr4d |  |