Multi-way versus One-way Constraints in User Interfaces: Experience
with the DeltaBlue Algorithm
Authors: Michael Sannella, John Maloney, Bjorn Freeman-Benson, and Alan
Borning
Software--Practice and Experience, Vol. 23 No. 5, (May 1993),
pages 529-566. Preprint published as UW Tech Report 92-07-05.
Abstract
The efficient satisfaction of constraints is essential to the performance
of constraint-based user interfaces. In the past, most constraint-based
user interfaces have used one-way rather than multi-way constraints
because of a widespread belief that one-way constraints were more
efficient. In this paper we argue that many user interface construction
problems are handled more naturally and elegantly by multi-way constraints
than by one-way constraints. We present pseudocode for an incremental
multi-way constraint satisfaction algorithm, DeltaBlue, and describe
experience in using the algorithm in two user interface toolkits. Finally,
we provide performance figures demonstrating that multi-way constraint
solvers can be entirely competitive in performance with one-way constraint
solvers.
full paper (compressed postscript)
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