reformulation of the Riemann Hypothesis.

There has been a surge of interest of late in an old result of Nyman and Beurling giving a Hilbert space formulation of the Riemann Hypothesis. Many authors have contributed to this circle of ideas, culminating in a beautiful refinement due to Baez-Duarte. The purpose of this little survey is to dis-entangle the resulting web of complications, and reveal the essential simplicity of the main results. Let H denote the weighted l2-space consisting of all sequences a = {an: n ∈ N} of complex numbers such that n=