The Indigo Algorithm

Authors: Alan Borning, Richard Anderson, and Bjorn Freeman-Benson

Published as UW Tech Report 96-05-01.


Inequality constraints are useful for specifying various aspects of user interfaces, such as constraints that one window is to the left of another, or that an object is contained within a rectangle. However, current local propagation constraint solvers can't handle inequality constraints. We present Indigo, an efficient local propagation algorithm for satisfying acyclic constraint hierarchies, including inequality constraints.

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