Appendix B: Concepts from the Approximation Theory
Danilo P. Mandic, Jonathon A. Chambers · 2001
Concepts from the Approximation TheoryDefinition B.1.1 (see Mhaskar and Micchelli 1992).The function σ : R → R (not necessarily continuous) is called a Kolmogorov function, if for any integer s 1, any compact set K ⊂ R s , any continuous function f : K → R and any ε > 0, there exists an integer N , numbers c k , t k ∈ R and λ k ∈ R s , 1 k N , possibly depending upon s, K, f , ε, such that