An SL(2,R) Model of Constrained Systems: Algebraic Constraint Quantization

A reparametrization invariant model, introduced by Montesinos, Rovelli and Thiemann, possessing an SL(2,R) gauge symmetry is treated along the guidelines of an algebraic constraint quantization scheme that translates the vanishing of the constraints into representation conditions for the algebra of observables. The application of this algebraic scheme to the SL(2,R) model yields an unambiguous identification of the physical representation of the algebra of observables.