“…Some popular ones include tree search (Christofides and Beasley 1982;Bartezzaghi and Colorni 1981), Lagrangian relaxation with branch and bound (Narula, Ogbu and Samuelsson, 1977;Khumawala, 1972;Galvao, 1980;Erlenkotter, 1978;ReVelle and Swain, 1970), tabu search (Ohlemüller, 1997;Rolland et al, 1996), and other heuristic and decision techniques (Hribara and Daskin, 1997;Hansen, Mladenovic and Taillard, 1998;Drezner and Guyse, 1999), as well as Kohonen maps (Lozano, Guerrero, Onieva and Larrañeta, 1998). A summary of past results is given in Table 1.…”