<f>1/R</f> gravity and scalar-tensor gravity

We point out that extended gravity theories, the Lagrangian of which is an arbitrary function of scalar curvature <f>R</f>, are equivalent to a class of the scalar-tensor theories of gravity. The corresponding gravity theory is <f>ω=0</f> Brans–Dicke gravity with a potential for the Brans–Dicke scalar field, which is not compatible with solar system experiments if the field is very light: the case when such modifications become important recently. [Copyright &y& Elsevier]