Cartographic name placement with Prolog

A major problem in computer cartography is how to place names on maps so they are clearly associated with the features they annotate, while avoiding overlap with other names and features. The logic programming language, Prolog, can be used to express the name-placement problem as a set of rules, referring primarily to the identification of free space, the generation of trial label positions, and the resolution of conflict between these positions. Cartographic features can be specified either explicitly as facts in the Prolog database or implicitly by presenting Prolog with the results of a prior analysis of potential label positions. The Prolog inference mechanism can then determine whether there is a combination of label positions that satisfies the rules of placement