Optimal singular controls for VSEIR model of Tuberculosis

The optimality singular controls of a VSEIR model of Tuberculosis are analyzed in this paper. There are controls that correspond to time- vary the vaccination and treatment schedules. A Hamiltonian (H) of the model is defined. The model is splited into separate one-dimensional problems, the so-called switching functions. The extreme occurs when a switching function disappears suddenly over an open interval. In which the derivatives of switching function must disappears suddenly and this typically allows computing such a control. The second-order of the function is not vanishing, which satisfied Legendre-Clebsh condition, and thus the controls of these kinds are called singular. In this work, our main emphasis is on a complete analysis of the optimum properties corresponding to trajectories. The result shows that vaccination control is singular, but treatment is not. This means that the model reached the optimality control for vaccination schedule, but not treatment schedule.