Stuart A. Grant

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Variable ordering heuristics can have a profound eeect on the performance of backtracking search algorithms for constraint satisfaction problems. The smallest-remaining-domain heuristic is a commonly-used dynamic variable ordering heuristic, used in conjunction with algorithms such as forward checking which look ahead at the eeects of each variable(More)
Randomly-generated constraint satisfaction problems go through a phase transition as the constraint tightness varies. Loose constraints give anèasy-soluble' region, where problems have many solutions and are almost always easy to solve. However, in this region, systematic search algorithms may occasionally encounter problems which are extremely expensive to(More)
Many types of problem exhibit a phase transition as a problem parameter is varied, from a region where most problems are easy and soluble to a region where most problems are easy but insoluble. In the intervening phase transition region, the median problem dii-culty is greatest. However, occasional exceptionally hard problems (ehps) can be found in the easy(More)
In this paper, we study two recently presented algorithms employing a \full look-ahead" strategy: MAC (Maintaining Arc Consistency); and the hybrid MAC-CBJ, which combines connict-directed backjumping capability with MAC. We observe their behaviour with respect to the phase transition properties of randomly-generated binary constraint satisfaction problems,(More)
Continuous interscalene brachial plexus blockade traditionally requires a hospital stay for local anesthetic infusion, and achieving consistent catheter insertion may be difficult. Incorporating long-acting pain relief from a continuous peripheral nerve block, with a reliable method of catheter insertion, and a self-contained infusion system would be a(More)
We give some dos and don'ts for those analysing algorithms experimentally. We illustrate these with many examples from our own research on the study of algorithms for NP-complete problems such as satissability and constraint satisfaction. Where we have not followed these maxims, we have suuered as a result.
We investigated the safety of a patient-maintained system that allows individuals to operate a target-controlled infusion of propofol to achieve sedation. Ten healthy volunteers were recruited and instructed to try to anaesthetize themselves with the system. A target-controlled infusion of propofol was set to deliver a target propofol concentration of 1(More)
We studied psychomotor performance in 10 healthy volunteers during recovery after a target-controlled infusion of propofol. Choice reaction time, dual task tracking with secondary reaction time and a within-list recognition task were assessed at target blood propofol concentrations of 0.8, 0.4 and 0.2 microgram ml-1. Performance was impaired most at the(More)