13,231 research outputs found
Robust Classification for Imprecise Environments
In real-world environments it usually is difficult to specify target
operating conditions precisely, for example, target misclassification costs.
This uncertainty makes building robust classification systems problematic. We
show that it is possible to build a hybrid classifier that will perform at
least as well as the best available classifier for any target conditions. In
some cases, the performance of the hybrid actually can surpass that of the best
known classifier. This robust performance extends across a wide variety of
comparison frameworks, including the optimization of metrics such as accuracy,
expected cost, lift, precision, recall, and workforce utilization. The hybrid
also is efficient to build, to store, and to update. The hybrid is based on a
method for the comparison of classifier performance that is robust to imprecise
class distributions and misclassification costs. The ROC convex hull (ROCCH)
method combines techniques from ROC analysis, decision analysis and
computational geometry, and adapts them to the particulars of analyzing learned
classifiers. The method is efficient and incremental, minimizes the management
of classifier performance data, and allows for clear visual comparisons and
sensitivity analyses. Finally, we point to empirical evidence that a robust
hybrid classifier indeed is needed for many real-world problems.Comment: 24 pages, 12 figures. To be published in Machine Learning Journal.
For related papers, see http://www.hpl.hp.com/personal/Tom_Fawcett/ROCCH
Hidden Variables or Positive Probabilities?
Despite claims that Bell's inequalities are based on the Einstein locality
condition, or equivalent, all derivations make an identical mathematical
assumption: that local hidden-variable theories produce a set of
positive-definite probabilities for detecting a particle with a given spin
orientation. The standard argument is that because quantum mechanics assumes
that particles are emitted in a superposition of states the theory cannot
produce such a set of probabilities. We examine a paper by Eberhard, and
several similar papers, which claim to show that a generalized Bell inequality,
the CHSH inequality, can be derived solely on the basis of the locality
condition, without recourse to hidden variables. We point out that these
authors nonetheless assumes a set of positive-definite probabilities, which
supports the claim that hidden variables or "locality" is not at issue here,
positive-definite probabilities are. We demonstrate that quantum mechanics does
predict a set of probabilities that violate the CHSH inequality; however these
probabilities are not positive-definite. Nevertheless, they are physically
meaningful in that they give the usual quantum-mechanical predictions in
physical situations. We discuss in what sense our results are related to the
Wigner distribution.Comment: 19 pages, 2 ps files This is a second replacement. In this version we
include an analysis of yet another version of Bell's theorem which has been
brought to our attention. We also discuss in what sense our results are
related to the Wigner distributio
Last Settler’s Syndrome and Land Use Change in Southern Appalachia
In many rural areas land use patterns are shifting from agriculture or woodland to residential development. This is especially true in areas possessing significant natural amenities like the sweeping vistas, white-water rivers, and blue-ridged mountains of Southern Appalachia. As in-migration increases, decisions about land use can become heated as the “newcomers” square off with long-time residents. Understanding how various groups value both the land (as productive resource) and the landscape (as scenic amenity) can help address potential conflict when land use changes. Two independent projects in Watauga County, North Carolina, reflect attempts to understand perspectives on land use through an economic framework and to address land use change from an environmental perspective. Both projects reveal evidence of “last settler’s syndrome”—a tendency among individuals to place a high value on what initially attracted them to a specific place. Both also reveal situations of potential conflict when ideas about land use clash as well as situations for cooperation as various groups share values about land use. Key Words:
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