Indigo: A Local Propagation Algorithm for Inequality Constraints
Authors: Alan Borning, Richard Anderson, and Bjorn Freeman-Benson
In Proceedings of the 1996 ACM Symposium on User Interface Software and
Technology, pages 129-136.
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.
full paper (compressed postscript)
A companion technical report, "The Indigo
Algorithm", UW tech report 96-05-01, contains additional material
(proofs of theorems and definitions of interval operations).
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