| Step | Hyp | Ref | Expression | 
						
							| 1 |  | logcn.d |  |-  D = ( CC \ ( -oo (,] 0 ) ) | 
						
							| 2 |  | eqid |  |-  ( TopOpen ` CCfld ) = ( TopOpen ` CCfld ) | 
						
							| 3 | 2 | recld2 |  |-  RR e. ( Clsd ` ( TopOpen ` CCfld ) ) | 
						
							| 4 |  | 0re |  |-  0 e. RR | 
						
							| 5 |  | iocmnfcld |  |-  ( 0 e. RR -> ( -oo (,] 0 ) e. ( Clsd ` ( topGen ` ran (,) ) ) ) | 
						
							| 6 | 4 5 | ax-mp |  |-  ( -oo (,] 0 ) e. ( Clsd ` ( topGen ` ran (,) ) ) | 
						
							| 7 |  | tgioo4 |  |-  ( topGen ` ran (,) ) = ( ( TopOpen ` CCfld ) |`t RR ) | 
						
							| 8 | 7 | fveq2i |  |-  ( Clsd ` ( topGen ` ran (,) ) ) = ( Clsd ` ( ( TopOpen ` CCfld ) |`t RR ) ) | 
						
							| 9 | 6 8 | eleqtri |  |-  ( -oo (,] 0 ) e. ( Clsd ` ( ( TopOpen ` CCfld ) |`t RR ) ) | 
						
							| 10 |  | restcldr |  |-  ( ( RR e. ( Clsd ` ( TopOpen ` CCfld ) ) /\ ( -oo (,] 0 ) e. ( Clsd ` ( ( TopOpen ` CCfld ) |`t RR ) ) ) -> ( -oo (,] 0 ) e. ( Clsd ` ( TopOpen ` CCfld ) ) ) | 
						
							| 11 | 3 9 10 | mp2an |  |-  ( -oo (,] 0 ) e. ( Clsd ` ( TopOpen ` CCfld ) ) | 
						
							| 12 |  | unicntop |  |-  CC = U. ( TopOpen ` CCfld ) | 
						
							| 13 | 12 | cldopn |  |-  ( ( -oo (,] 0 ) e. ( Clsd ` ( TopOpen ` CCfld ) ) -> ( CC \ ( -oo (,] 0 ) ) e. ( TopOpen ` CCfld ) ) | 
						
							| 14 | 11 13 | ax-mp |  |-  ( CC \ ( -oo (,] 0 ) ) e. ( TopOpen ` CCfld ) | 
						
							| 15 | 1 14 | eqeltri |  |-  D e. ( TopOpen ` CCfld ) |