@TECHREPORT\{IMM2004-03373,
    author       = "V. Mak and T. Thomadsen",
    title        = "Facets for the Cardinality Constrained Quadratic Knapsack Problem and the Quadratic Selective Travelling Salesman Problem",
    year         = "2004",
    month        = "nov",
    keywords     = "Quadratic Knapsack; Quadratic Selective Travelling Salesman; Polyhedral Analysis; Facets",
    number       = "",
    series       = "IMM-Technical Report-2004-19",
    institution  = "Informatics and Mathematical Modelling, Technical University of Denmark, {DTU}",
    address      = "Richard Petersens Plads, Building 321, {DK-}2800 Kgs. Lyngby",
    type         = "",
    url          = "http://www2.compute.dtu.dk/pubdb/pubs/3373-full.html",
    abstract     = "A well-known extension of the Travelling Salesman Problem (TSP) is the Selective (or Prize-collecting) {TSP}: In addition to the edge-costs, each node has an associated reward (denoted the node-reward) and instead of visiting all nodes, only profitable nodes are visited. The Quadratic Selective {TSP} (QSTSP) has the additional complications: (1) each pair of nodes have an associated reward (denoted the edge-reward) which can be gained only if both nodes are visited; and (2) a constraint on the number of nodes selected is imposed, which we refer to as the cardinality constraint.  The objective of an {QSTSP} is to maximize the total node-reward and edge-rewards gained minus the edge-costs incurred subject to the satisfaction of the cardinality constraint."
}