On linear programming formulations for the TSP polytope

This paper is making some waves in Operations Research circles:

    We solve a 20-year old problem posed by M. Yannakakis and prove 
    that there exists no polynomial-size linear program (LP) whose 
    associated polytope projects to the traveling salesman polytope, 
    even if the LP is not required to be symmetric. 

This argument is independent of the P-vs-NP argument, as it doesn't consider the encoding length of the coefficients.