“…See, for example, Swofford andWhitney (1987, 1988), Barnhart and Whitney (1988), Patterson (1991), Belongia and Chrystal (1991), Choi and Sosin (1992), Swofford and Whitney (1994), Jones and Mazzi (1996), Cox (1997), Fisher and Fleissig (1997), Rickertsen (1998), Spencer (2002, Whitney (2003, 2008), Swofford (2005), Serletis and Rangel-Ruiz (2005), Jones, Dutkowsky, and Elger (2005), Jha and Longjam (2006), Blundell, Browning, and Crawford (2007), Hjertstrand (2007, 2009), Elger, Jones, Edgerton, and Binner (2008, Elger and Jones (2008), and Drake and Fleissig (2008). 7 We refer to Garey and Johnson (1979) for an introduction into the theory of np-completeness.…”