This paper concerns the uniform random generation and the approximate counting of combinatorial structures admitting an ambiguous description. We propose a general framework to study the complexity of these problems and present some applications to specific classes of languages. In particular, we give a uniform random generation algorithm for finitely ambiguous contextfree languages of the same...

For a compact subset K of the complex plane C, let C(K) denote algebra continuous functions on K. an open U?K, A(K,U)?C(K) be that are analytic in U. We show there exists ??A(K,U) so each f?A(K,U) can uniformly approximated by {pn+qn?} K, where pn and qn polynomials z. In particular, ? chosen as Cauchy transform finite positive measure ? compactly supported C?U. Recent developments capacity pro...