H. Paul Williams

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Many discrete optimization problems can be formulated as either integer linear programming problems or constraint satisfaction problems. Although ILP methods appear to be more powerful, sometimes constraint programming can solve these problems more quickly. This paper describes a problem in which the difference in performance between the two approaches was(More)
Large practical linear and integer programming problems are not always presented in a form which is the most compact representation of the problem. Such problems are likely to posses generalized upper bound(GUB) and related structures which may be exploited by algorithms designed to solve them efficiently. The steps of an algorithm which by repeated(More)
The use of predicates to state constraints in Constraint Satisfaction is explained. If, as an alternative, the traditional approach of Integer Programming (IP) is used, it is desirable to model these constraints so as to give as tight a linear programming relaxation as possible. One of the most commonly used predicates is the “all_different” predicate.(More)
Sorting nexins (Snxs) are a recently discovered family of conserved hydrophilic cytoplasmic proteins that have been found associated with membranes of the endocytic system and that are implicated in the trafficking of many endosomal membrane proteins, including the epidermal growth factor receptor and transferrin receptor. Snx proteins are partly defined by(More)
We report here an in vivo study of kinesin heavy chain (KHC) functions in yeast. We have identified in Schizosaccharomyces pombe a kinesin motor gene, klp3(+), which has the highest homology to the Neurospora crassa KHC. Using indirect immunofluorescence, HA epitope-tagged Klp3 protein is cytoplasmic and appears as one to a few distinct patches that are(More)
Mutations in the enzyme glycyl-tRNA synthetase (GARS) cause motor and sensory axon loss in the peripheral nervous system in humans, described clinically as Charcot-Marie-Tooth type 2D or distal spinal muscular atrophy type V. Here, we characterise a new mouse mutant, Gars(C201R), with a point mutation that leads to a non-conservative substitution within(More)
Glycogen synthase kinase 3 (GSK3) is a central regulator of metazoan development and the Dictyostelium GSK3 homologue, GskA, also controls cellular differentiation. The originally derived gskA-null mutant exhibits a severe pattern formation defect. It forms very large numbers of pre-basal disc cells at the expense of the prespore population. This defect(More)