| Step | Hyp | Ref | Expression | 
						
							| 1 |  | zringbas |  | 
						
							| 2 |  | eqid |  | 
						
							| 3 |  | zsubrg |  | 
						
							| 4 |  | subrgsubg |  | 
						
							| 5 | 3 4 | ax-mp |  | 
						
							| 6 |  | df-zring |  | 
						
							| 7 | 6 | subggrp |  | 
						
							| 8 | 5 7 | mp1i |  | 
						
							| 9 |  | 1zzd |  | 
						
							| 10 |  | ax-1cn |  | 
						
							| 11 |  | cnfldmulg |  | 
						
							| 12 | 10 11 | mpan2 |  | 
						
							| 13 |  | 1z |  | 
						
							| 14 |  | eqid |  | 
						
							| 15 | 14 6 2 | subgmulg |  | 
						
							| 16 | 5 13 15 | mp3an13 |  | 
						
							| 17 |  | zcn |  | 
						
							| 18 | 17 | mulridd |  | 
						
							| 19 | 12 16 18 | 3eqtr3rd |  | 
						
							| 20 |  | oveq1 |  | 
						
							| 21 | 20 | rspceeqv |  | 
						
							| 22 | 19 21 | mpdan |  | 
						
							| 23 | 22 | adantl |  | 
						
							| 24 | 1 2 8 9 23 | iscygd |  | 
						
							| 25 | 24 | mptru |  |