Let K1 and K2 be solid cones in Rn and Rm respectively, and let A be a linear operator such that AK1⊆K2. Necessary and sufficient conditions for the existence of various kinds of generalized inverses of A taking K2 into K1 are given. Projections which belong to π(K), the set of all linear operators that preserve a are studied. In particular, it is proved that a projection P in π(K) is a simplicial nonnegative linear combination of its rank-one operators iff Im P∩K is a simplical cone. An open question of Burns, Fiedler, and Haynsworth concerning minimal generating matrices of polyhedral cones is also extended and answered affirmatively.
Linear Algebra and Its Applications 40, pp.189-202