BOOKS OF RtfiDIfGS - PAHO/WHO

REVELLE
ET Al..
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Fig. 4. Another maximal covering approach to the
location problem of Fig. 2, with 15-minute constraint
relaxed. Facilities (circled dots) are placed so that
95 percent of the population is within 10-unit limit
(dashed lines) from tome facility; 98 percent is
atill within 15-unit limits (solid lines).
mize the population within 10 units, given tice countra;int of keeping
the entire population within 15 unitu. In the new configuration 55
percent of the population is within 10 uniht of a facility. Although
the location set model nuight have foutd thiis solution by chance, tihe
probability of its doing so is low; in general. onily explicit optitnization
using the maximal tovering model cain hc expected to yield sudc
solutions.
If the rigid constraint of complete cever-gec witil¡n as: ouiter liiit
is reLaxed, alternative configuratiois witl puosilly molu e sic'l'l charirIAMit
acieristiis may be derived. Figure 4 depicts a solutioii ohtaiiicd witi
SRaLaaiUR tbhe standard of 15 units discarded. Fiv'. facilities can cover '.Y5 percent
ol the population witlin 10 units wilce leavislg ulry '2 l.'cint
o the popuilation otusieir a 15.unit p