  The combinatorial diameter of a polytope $P$ is the maximum value of a
shortest path between two vertices of $P$, where the path uses the edges of $P$
only. In contrast to the combinatorial diameter, the circuit diameter of $P$ is
defined as the maximum value of a shortest path between two vertices of $P$,
where the path uses potential edge directions of $P$ i.e., all edge directions
that can arise by translating some of the facets of $P$.
  In this paper, we study the circuit diameter of polytopes corresponding to
classical combinatorial optimization problems, such as the Matching polytope,
the Traveling Salesman polytope and the Fractional Stable Set polytope.
