  In this paper we consider the Recoverable Traveling Salesman Problem (TSP).
Here the task is to find two tours simultaneously, such that the intersection
between the tours is at least a given minimum size, while the sum of travel
distances with respect to two different distance metrics is minimized. Building
upon the classic double-tree method, we derive a 4-approximation algorithm for
the RecoverableTSP. We also show that if the required size of the intersection
between the tours is constant, a 2-approximation guarantee can be achieved,
even if more than two tours need to be constructed. We discuss consequences for
approximability results in the more general area of recoverable robust
optimization.
