| Step | Hyp | Ref | Expression | 
						
							| 1 |  | imsdfn.1 |  |-  X = ( BaseSet ` U ) | 
						
							| 2 |  | imsdfn.8 |  |-  D = ( IndMet ` U ) | 
						
							| 3 |  | eqid |  |-  ( normCV ` U ) = ( normCV ` U ) | 
						
							| 4 | 1 3 | nvf |  |-  ( U e. NrmCVec -> ( normCV ` U ) : X --> RR ) | 
						
							| 5 |  | eqid |  |-  ( -v ` U ) = ( -v ` U ) | 
						
							| 6 | 1 5 | nvmf |  |-  ( U e. NrmCVec -> ( -v ` U ) : ( X X. X ) --> X ) | 
						
							| 7 |  | fco |  |-  ( ( ( normCV ` U ) : X --> RR /\ ( -v ` U ) : ( X X. X ) --> X ) -> ( ( normCV ` U ) o. ( -v ` U ) ) : ( X X. X ) --> RR ) | 
						
							| 8 | 4 6 7 | syl2anc |  |-  ( U e. NrmCVec -> ( ( normCV ` U ) o. ( -v ` U ) ) : ( X X. X ) --> RR ) | 
						
							| 9 | 5 3 2 | imsval |  |-  ( U e. NrmCVec -> D = ( ( normCV ` U ) o. ( -v ` U ) ) ) | 
						
							| 10 | 9 | feq1d |  |-  ( U e. NrmCVec -> ( D : ( X X. X ) --> RR <-> ( ( normCV ` U ) o. ( -v ` U ) ) : ( X X. X ) --> RR ) ) | 
						
							| 11 | 8 10 | mpbird |  |-  ( U e. NrmCVec -> D : ( X X. X ) --> RR ) |