let X be non empty set ; :: thesis: for Y being RealNormSpace
for f being bounded Function of X,the carrier of Y holds (BoundedFunctionsNorm X,Y) . f = sup (PreNorms f)

let Y be RealNormSpace; :: thesis: for f being bounded Function of X,the carrier of Y holds (BoundedFunctionsNorm X,Y) . f = sup (PreNorms f)
let f be bounded Function of X,the carrier of Y; :: thesis: (BoundedFunctionsNorm X,Y) . f = sup (PreNorms f)
reconsider f9 = f as set ;
f in BoundedFunctions X,Y by Def5;
hence (BoundedFunctionsNorm X,Y) . f = sup (PreNorms (modetrans f9,X,Y)) by Def9
.= sup (PreNorms f) by Th16 ;
:: thesis: verum