Geospatial Optimization Problems

There are numerous applications which require the ability to take certain actions (e.g. distribute money, medicines, people etc.) over a geographic region. A disaster relief organization must allocate people and supplies to parts of a region after a disaster. A public health organization must allocate limited vaccine to people across a region. In both cases, the organization is trying to optimize something (e.g. minimize expected number of people with a disease).

In April, at the IEEE Network Science Workshop, we introduced “geospatial optimization problems” (GOPs) where an organization has limited resources and budget to take actions in a geographic area. The actions result in one or more properties changing for one or more locations. There are also certain constraints on the combinations of actions that can be taken.

In the paper, we study two types of GOPs – goal-based and benefit-maximizing (GBGOP and BMGOP respectively). A GBGOP ensures that certain properties must be true at specified locations after the actions are taken while a BMGOP optimizes a linear benefit function. We show both problems to be NP-hard and prove limits on approximation for both problems. We present integer programs for both GOPs that provide exact solutions. We also correctly reduce the number of variables in for the GBGOP integer constraints. For BMGOP, we present the BMGOP-Compute algorithm that runs in PTIME and provides a reasonable approximation guarantee in most cases.

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The Network Science Center (NSC) brings together service members, civilians, and cadets to research and develop significant contributions in the study of network representations of physical, biological, and social phenomena leading to predictive models. The NSC is a thought-leader in this emerging discipline and addresses Army-specific and related Network Science challenges. The NSC also provides relevant educational opportunities for current and future Army leaders.