Some new bounds for Epsilon-nets

Abstract

Given any natural number d, 0 < ε < 1, let ƒd(ε) denote the smallest integer ƒ such that every range space of Vapnik-Chervonenkis dimension d has an ε-net of size at most ƒ We solve a problem of Haussler and Welzl by showing that if d ≥ 2, then ƒd(ε) > 1/48 d/ε log 1/ ε which is not far from being optimal, if d is fixed and ε → 0. Further, we prove that ƒ1(ε) = max(2,⌈1/ε⌉ - 1), and similar bounds are established for some special classes of range spaces of Vapnik-Chervonenkis dimension three.