The Indigo Algorithm

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

Published as UW Tech Report 96-05-01.

Abstract

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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