Representation ofLp-norms and isometric embedding inLp-spaces
- Cite this article as:
- Neyman, A. Israel J. Math. (1984) 48: 129. doi:10.1007/BF02761158
For fixed 1≦p<∞ theLp-semi-norms onRn are identified with positive linear functionals on the closed linear subspace ofC(Rn) spanned by the functions |<ξ, ·>|p, ξ∈Rn. For every positive linear functional σ, on that space, the function Φσ:Rn→R given by Φσ is anLp-semi-norm and the mapping σ→Φσ is 1-1 and onto. The closed linear span of |<ξ, ·>|p, ξ∈Rn is the space of all even continuous functions that are homogeneous of degreep, ifp is not an even integer and is the space of all homogeneous polynomials of degreep whenp is an even integer. This representation is used to prove that there is no finite list of norm inequalities that characterizes linear isometric embeddability, in anyLp unlessp=2.