Order-automorphisms of the set of bounded observables

Let H be a complex Hilbert space and denote by B-s(H) the set of all self-adjoint bounded linear operators on H. In this article we describe the form of all bijective maps (no linearity or continuity is assumed) on B-s(H) which preserve the order less than or equal to in both directions. (C) 2001 American Institute of Physics.