The purpose of this demonstration is to help you develop intuition for how various constraint propagation methods perform. The particular problem solved is that of coloring maps, that is, the problem of allocating colors (in general, resources) to states (in general, tasks), such that states with a common border have different colors.

The Map menu item on the menu bar allows you to switch between a map of the United States and a toy country that, although simple, cannot be handled without joining the depth-first color assignment with some form of constraint checking.

The Type menu item on the menu bar provides access to a variety of constraint checking methods ranging from no checking to too-much checking. The Arrangement item varies the difficulty of the United States coloring problem by changing the order in which the states are colored by depth-first color assignment. The Colors item enables you to decide how many colors are used. The Speed item enables you to alter how fast the coloring movie plays.

The Search button initiates your constraint-based search for consistent colors. Other buttons have obvious purposes.

Constraint-Propagation and Resource Allocation Java® Demonstration 

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Testing was done with Java® 1.4, running in Netscape Navigator 7.02 and in Internet Explorer 6.0.

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