The Cauchy problem for metric-affine f(R)-gravity in the presence of perfect-fluid matter

The Cauchy problem for metric-affine f(R)-gravity in the manner of Palatini and with torsion, in the presence of perfect fluid matter acting as a source, is discussed following the well-known Bruhat prescriptions for general relativity. The problem results in being well formulated and well posed when the perfect-fluid form of the stress-energy tensor is preserved under conformal transformations and the set of viable f(R)-models is not empty. The key role of conservation laws in the Jordan and in the Einstein frame is also discussed.