Constrained Markov control processes in Borel spaces: the discounted case

We consider constrained discounted-cost Markov control processes in Borel spaces, with unbounded costs. Conditions are given for the constrained problem to be solvable, and also equivalent to an equality-constrained (EC) linear program. In addition, it is shown that there is no duality gap between EC and its dual program EC^*, and that, under additional assumptions, also EC^* is solvable, so that in fact the strong duality condition holds. Finally, a Farkas-like theorem is included, which gives necessary and sufficient conditions for the primal program EC to be consistent.