“…Different HALPs have been studied in the literature. For instance, HALPs with a cardinality constraint on the number of opened hub arcs (Campbell et al, 2005), HALPs that incorporate setup costs for the hub nodes and hubs arcs (Contreras and Fernández, 2014;Gelareh et al, 2015), or HALPs that impose particular topological structures, such as tree-star (Contreras et al, 2010), star-star (Labbé and Yaman, 2008), ringstar , and hub lines (Martins de Sá et al,015a,b). We can also relate HNDPPs to studies that focus on the design of hub networks in airline transportation (see, for instance, Aykin, 1995;Jaillet et al, 1996;Sasaki et al, 1999;Bryan and O'Kelly, 1999;O'Kelly, 2012;Saberi and Mahmassani, 2013).…”