From projectors to 1MP and MP1 generalized inverses and their induced partial orders

This paper deals with new generalized inverses of rectangular complex matrices, namely 1MP and MP1-inverses. They are constructed from oblique projectors represented by means of inner generalized inverses, by using an adequate equivalence relation, and then passing to the quotient set. We give characterizations and general expressions for 1MP and MP1-inverses. As applications, the binary relations induced for these new generalized inverses are proved to be partial orders.