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Popular Ensemble Methods: An Empirical Study

Journal of Artificial Intelligence Research

An ensemble consists of a set of individually trained classifiers (such as neural networks or decision trees) whose predictions are combined when classifying novel instances. Previous research has shown that an ensemble is often more accurate than any of the single classifiers in the ensemble. Bagging (Breiman, 1996c) and Boosting (Freund & Shapire, 1996; Shapire, 1990) are two relatively new but popular methods for producing ensembles. In this paper we evaluate these methods on 23 data sets using both neural networks and decision trees as our classification algorithm. Our results clearly indicate a number of conclusions. First, while Bagging is almost always more accurate than a single classifier, it is sometimes much less accurate than Boosting. On the other hand, Boosting can create ensembles that are less accurate than a single classifier -- especially when using neural networks. Analysis indicates that the performance of the Boosting methods is dependent on the characteristics of the data set being examined. In fact, further results show that Boosting ensembles may overfit noisy data sets, thus decreasing its performance. Finally, consistent with previous studies, our work suggests that most of the gain in an ensemble's performance comes in the first few classifiers combined; however, relatively large gains can be seen up to 25 classifiers when Boosting decision trees.


Background to Qualitative Decision Theory

AI Magazine

This article provides an overview of the field of qualitative decision theory: its motivating tasks and issues, its antecedents, and its prospects. Qualitative decision theory studies qualitative approaches to problems of decision making and their sound and effective reconciliation and integration with quantitative approaches. Although it inherits from a long tradition, the field offers a new focus on a number of important unanswered questions of common concern to AI, economics, law, psychology, and management.


AAAI News

AI Magazine

Note 2. Operations Note 3. Investments at December 31, 1998 AAAI was formed in 1979 as a scientific Investments are stated at fair market value since it is readily determinable and the society, to encourage the basic knowledge investments are not necessarily being held to any maturity. Realized and unrealized of what constitutes intelligent thought gains and losses are reported in the statement of activities.


JAIR at Five

AI Magazine

The "Journal of Artificial Intelligence Research (JAIR) was one of the first scientific journals distributed over the web. It has now completed over five years of successful publication. Electronic publishing is reshaping the way academic work is disseminated, and JAIR is leading the way toward a future where scientific articles are freely and easily accessible to all. This report describes how the journal has evolved, its "grassroots" philosophy, and prospects for the future.



Recent Advances in AI Planning

AI Magazine

The past five years have seen dramatic advances in planning algorithms, with an emphasis on propositional methods such as GRAPHPLAN and compilers that convert planning problems into propositional conjunctive normal form formulas for solution using systematic or stochastic SAT methods. Related work, in the context of spacecraft control, advances our understanding of interleaved planning and execution. In this survey, I explain the latest techniques and suggest areas for future research.


Extensible Knowledge Representation: the Case of Description Reasoners

Journal of Artificial Intelligence Research

This paper offers an approach to extensible knowledge representation and reasoning for a family of formalisms known as Description Logics. The approach is based on the notion of adding new concept constructors, and includes a heuristic methodology for specifying the desired extensions, as well as a modularized software architecture that supports implementing extensions. The architecture detailed here falls in the normalize-compared paradigm, and supports both intentional reasoning (subsumption) involving concepts, and extensional reasoning involving individuals after incremental updates to the knowledge base. The resulting approach can be used to extend the reasoner with specialized notions that are motivated by specific problems or application areas, such as reasoning about dates, plans, etc. In addition, it provides an opportunity to implement constructors that are not currently yet sufficiently well understood theoretically, but are needed in practice. Also, for constructors that are provably hard to reason with (e.g., ones whose presence would lead to undecidability), it allows the implementation of incomplete reasoners where the incompleteness is tailored to be acceptable for the application at hand.


Automated Deduction: Looking Ahead

AI Magazine

To not only proving new mathematical obtain broader input, especially from countries results by computer but also formally verifying outside North America, a call for commentaries the correctness of (certain properties of) computer was issued to the automated deduction community.


Applied AI News

AI Magazine

The expert system maintains a stable kiln temperature and has facilitated the standardization of control procedures. American Airlines (Fort Worth, Tex.) consortium representing 60 percent of Irvine Sensors (Costa Mesa, Calif.) has utilized speech-recognition technology all newspapers circulated in the United has received a contract from the U.S. to enhance its automated Kingdom, has developed an intelligent Army Space and Missile Defense Command flight information system, The technology will be used to classified ads. Calif.) has initiated a fingerprintbased to improve its underwriting process. Cooper Tire & Rubber (Findlay, that provides participants with access The company's rule-based paperless Ohio) has implemented a genetic to online banking services. The biometric personal lines processing application algorithm-based system to optimize software matches the fingerprint automates the procedure for evaluating its supply chain.