One-Sided Approximation of Functions

where :Yl denotes the orthogonal complement of Y (see [I]). Another example of this type of duality appears in one of the classical moment problems. Letfbe Bore1 measurable and bounded on [a,b], h,, . . ., h, a CebySev system on [a,b] and for a given positive Bore1 measure yO defined on [a,b] denote by C (y,,) the class of all positive Bore1 measures y which satisfy f.bhkdy=[hkdyo k= 1,2 ,..., n. We then have