“…In the current paper, the regression function of increments is given by the product of two components, namely of the linear directed force [V − p − − V + p + ] defined in [1] and the factor p + p − that changes the directed force in a neighborhood of boundary values −1 and +1. Such a nonlinear factor appears, for example, in the Wright-Fisher model (see, for example, [2, Chapter 10]).…”