Using multiflow formulations to solve the Steiner tree problem in graphs

We present three dfferent mixed integer linear models with a polynomial number of variables and constraints for the Steiner tree problem in graphs. The linear relaxations of these models are compared to show that a good (strong) linear relaxation can be a good approximation for the problem. We present computational results for the the STP OR-Library (J.E. Beasley) instances of type b, c, d and e.