Pre vious studies of one-fac ility minimax location problems are extended by pennitting the cost of travel to be gi ve n by any (stric tly) increa sing, continuous function of travel d ista nce. Previous solution procedures for the rec tilinear dista nce problem in the plane a nd for the proble m on a tree network are extended to these general cost fu nctions.Ke y words: Facility location; location the ory; minimax ; ne tworks.
. IntroductionMinimax location problems have rece ived considerable attention in the literature as models for locating fac ilities tha t are to provide eme rge ncy or convenient servi ce to a set of ex isting facilities. In most of these problems the re is given a set of ex isting facilities whose locati ons are represe nted as points in some space, and new fac ility locations are also to be spec ified as points in that space . A dista nce fun c ti on is chosen to represe nt the travel di stance between the new a nd ex isting fac ility locations . The minimax obj ective is to locate the new fac ilities so that the max imum di stance, or a fun cti on of di stance, between th e ne w and existing fac ility locations is minimized.Differe nt problems may be spec ified by the choice of the space a nd of the dista nce fun cti on used . Most of the problems in the literature may be pl aced into one of two classes: those using a no rm-de rived di sta nce in the space R" for some n , and those on a network using network distances. Also, diffe rent proble ms may be spec ifie d by the choice of the cost-representing fun cti ons of tra vel distance. These fun c ti ons a re refe rred to genericall y as "cost" funct io ns, but they may measure cost, time or some othe r fo rm of inconve ni e nce.This pa per considers one-fac ility minimax locati on p ro blems that permit quite ge neral cost fun ctions, name ly any continuous (strictl y) increasing fun c tion of the travel di stance. In th e prev ious cons iderations of minimax location proble ms, cost fun ctions we re assumed to be linea r, or in many cases the ide ntity fun cti on.The initial formul ation and analys is a re given for a pro blem in R " using norm-derived distances; however, the results obtain ed also hold for probl e ms on a ne tw ork and are disc ussed subsequentl y. In addition, for minimax location problems using rectilinear distance, this paper extends prev ious solution procedures to these more ge neral cost fun ctions in the space R2. For the problem on a tree network , previou s solution procedures are also e xtende d to the ge neral cost fun ctions.Most of the literature on minimax location problems has appeared in the las t te n years, although one ve rsion of the problem was first formul ated in 1857 as a " minimum covering s phe re problem." A brief historical review is given by Elzinga and H earn [6]1 who deal with the case involving the Eucl idean dista nce in R" and the identity cost fun ction. Elzinga and Hearn [5] and Na ir and Chandrasekaran [23] develop additional solution procedures for the same problem in R2. A multi-...