Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. The Signorini problem is a elastostatics problem in linear elasticity: it consists in finding the elastic equilibrium configuration of a anisotropic non-homogeneous elastic body, resting on a rigid frictionless surface and subject only to its mass forces. The name was coined by Gaetano Fichera to honour his teacher Signorini: the original name coined by him is problem with ambiguous boundary conditions.