Degeneracy and generalized solutions of optimal control problems

Degenerate optimal control problems are denned as those which have some latent passive differential or finite-difference constraints. They are typical for applications, but irregular for general methods. In this paper an analytical survey is presented of special methods developed starting from the 1960s and based, in essence, on detection and elimination of passive constraints, and some important results including most recent ones are given. Illustrative examples are considered.