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Determining whether a propositional theory is satissable is a prototypical example of an NP-complete problem. Further, a large number of problems that occur in knowledge-representation, learning, planning, and other ares of AI are essentially sat-issability problems. This paper reports on the most extensive set of experiments to date on the location and(More)
Many reasoning and optimization problems exhibit symmetries. Previous work has shown how special purpose algorithms can make use of these symmetries to simplify reasoning. We present a general scheme whereby symmetries are exploited by adding \symmetry-breaking" predicates to the theory. Our approach can be used on any propo-sitional satissability problem,(More)
Determining whether a propositional theory is satissable is a prototypical example of an NP-complete problem. Further, a large number of problems that occur in knowledge representation, learning, planning, and other areas of AI are essentially satissability problems. This paper reports on a series of experiments to determine the location of the crossover(More)
We report observation of a fine structure component in backscattered light from mucosal tissue which is periodic in wavelength. This structure is ordinarily masked by a diffusive background. We have identified the origin of this component as being due to light which is Mie scattered by surface epithelial cell nuclei. By analyzing the amplitude and frequency(More)
The Constraint Satisfaction Problem is a type of combinatorial search problem of much interest in Artiicial Intelligence and Operations Research. The simplest algorithm for solving such a problem is chronological backtracking, but this method suuers from a malady known as \thrashing," in which essentially the same subproblems end up being solved repeatedly.(More)
Considerable progress has been made in recent years in understanding and solving propositional satisfia-bilit y problems. Much of this work has been based on experiments on randomly generated 3SAT problems . One generally accepted shortcoming of this work is that it is not clear how the results and algorithms developed will carry over to " real "(More)
The work of liver stem cell biologists, largely carried out in rodent models, has now started to manifest in human investigations and applications. We can now recognize complex regenerative processes in tissue specimens that had only been suspected for decades, but we also struggle to describe what we see in human tissues in a way that takes into account(More)
A combination of targeted probes and new imaging technologies provides a powerful set of tools with the potential to improve the early detection of cancer. To develop a probe for detecting colon cancer, we screened phage display peptide libraries against fresh human colonic adenomas for high-affinity ligands with preferential binding to premalignant tissue.(More)
Qualitative reasoning can, and should, be decomposed into a model-building task, which creates a qualitative differential equation (QDE) as a model of a physical situation , and a qualitative simulation task, which starts with a QDE. and predicts the possible behaviors following from the model. In support of this claim, we present QPC, a model builder that(More)