Аннотация:This paper deals with models of pressure-independent and pressure dependent plasticity under plane strain conditions and provides a review of quantities satisfying the equation of telegraphy. This equation can be solved by the method of Riemann. In particular, the Green’s function for the equation of telegraphy is the Bessel function of zero order. An advantage of using the method of Riemann for solving boundary value problems is a high accuracy of solutions. Therefore, solutions found by this method can be used for verifying the accuracy of other methods. Some results presented in this paper are restricted to rigid plastic solids whereas others are independent of whether elastic strains are included. The last section of the paper concerns with the theory of ideal flows.