| Step | Hyp | Ref | Expression | 
						
							| 1 |  | maxidln1.1 |  |-  H = ( 2nd ` R ) | 
						
							| 2 |  | maxidln1.2 |  |-  U = ( GId ` H ) | 
						
							| 3 |  | eqid |  |-  ( 1st ` R ) = ( 1st ` R ) | 
						
							| 4 |  | eqid |  |-  ran ( 1st ` R ) = ran ( 1st ` R ) | 
						
							| 5 | 3 4 | maxidlnr |  |-  ( ( R e. RingOps /\ M e. ( MaxIdl ` R ) ) -> M =/= ran ( 1st ` R ) ) | 
						
							| 6 |  | maxidlidl |  |-  ( ( R e. RingOps /\ M e. ( MaxIdl ` R ) ) -> M e. ( Idl ` R ) ) | 
						
							| 7 | 3 1 4 2 | 1idl |  |-  ( ( R e. RingOps /\ M e. ( Idl ` R ) ) -> ( U e. M <-> M = ran ( 1st ` R ) ) ) | 
						
							| 8 | 7 | necon3bbid |  |-  ( ( R e. RingOps /\ M e. ( Idl ` R ) ) -> ( -. U e. M <-> M =/= ran ( 1st ` R ) ) ) | 
						
							| 9 | 6 8 | syldan |  |-  ( ( R e. RingOps /\ M e. ( MaxIdl ` R ) ) -> ( -. U e. M <-> M =/= ran ( 1st ` R ) ) ) | 
						
							| 10 | 5 9 | mpbird |  |-  ( ( R e. RingOps /\ M e. ( MaxIdl ` R ) ) -> -. U e. M ) |