@article {IOPORT.00737312,
    author       = {De Kort, J.B.J.M.},
    title        = {Bounds for the symmetric 2-peripatetic salesman problem.},
    year         = {1992},
    journal      = {Optimization},
    volume       = {23},
    number       = {4},
    issn         = {0233-1934},
    pages        = {357-367},
    publisher    = {Taylor \& Francis, Abingdon, Oxon},
    doi          = {10.1080/02331939208843770},
    abstract     = {Summary: The 2-Peripatetic Salesman Problem (2-PSP) minimizes the total length of 2 edge-disjoint Hamiltonian cycles. This type of problems arises in designing communication or computer networks, or whenever one aims to increase network reliability using disjoint tours. The NP-hardness of the 2-PSP is shown. Lower bound values are obtained by generalizing the 1- type approach for the TSP to a 2 edge-disjoint 1-trees approach for the 2-PSP. One can construct 2 edge-disjoint 1-trees using a greedy algorithm, into which a partitioning procedure is incorporated that runs $O(n\sp 2\log n)$ time. Upper bound solutions are obtained by two heuristics based on a lower bound solution and by a modified Savings heuristic for problems up to 140 cities.},
    identifier   = {00737312},
}