This paper presents a general mixed-norm minisum problem for locating a single facility in continuous space. It is assumed that several transportation modes exist between the new facility and a given set of fixed points (the customers), each mode being represented by a different ℓ <Subscript> p </Subscript> norm. A...</subscript>

A mixed graphG <Subscript>π</Subscript> contains both undirected edges and directed arcs. Ak-coloring ofG <Subscript>π</Subscript> is an assignment to its vertices of integers not exceedingk (also called colors) so that the endvertices of an edge have different colors and the tail of any arc has a smaller color than its head. The...</subscript></subscript>