@article{eprints1719, pages = {549--558}, publisher = {IEEE}, year = {2011}, author = {Giorgio Gnecco and Marcello Sanguineti}, journal = {IEEE Transactions on Information Theory}, title = {On a Variational Norm Tailored to Variable-Basis Approximation Schemes}, number = {1}, volume = {57}, abstract = {A variational norm associated with sets of computational units and used in function approximation, learning from data, and infinite-dimensional optimization is investigated. For sets Gk obtained by varying a vector y of parameters in a fixed-structure computational unit K(-,y) (e.g., the set of Gaussians with free centers and widths), upper and lower bounds on the GK -variation norms of functions having certain integral representations are given, in terms of the {\pounds}1-norms of the weighting functions in such representations. Families of functions for which the two norms are equal are described.}, keywords = {\$\{cal L\}\_1\$-norm, Approximation schemes, convex hulls, infinite-dimensional optimization, upper and lower bounds, variation with respect to a set}, url = {http://eprints.imtlucca.it/1719/} }