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document clustering,search strategies,and such like to work inside a computer
...Bibliographic remarks In recent years a vast literature on automatic classification has been generated
...A book and a report on cluster analysis with a computational emphasis are Anderberg [59]...Two papers worth singling out are Sibson [65]...Much of the early work in document clustering was done on the SMART project
...There are a number of areas in IR where automatic classification is used which have not been touched on in this chapter
...One further interesting area of application of clustering techniques is in the clustering of citation graphs
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Three AUTOMATIC CLASSIFICATION Introduction In this chapter I shall attempt to present a coherent account of classification in such a way that the principles involved will be sufficiently understood for anyone wishing to use classification techniques in IR to do so without too much difficulty
...A formal definition of classification will not be attempted;for our purposes it is sufficient to think of classification as describing the process by which a classificatory system is constructed
...How would you classify identify this?How are these best classified grouped?The first example refers to diagnosis whereas the second talks about classification proper
...In the context of information retrieval,a classification is required for a purpose
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Classification methods Let me start with a description of the kind of data for which classification methods are appropriate
...1 multi state attributes e
...2 binary state e
...3 numerical e
...4 probability distributions
...The fourth category of descriptors is applicable when the objects are classes
...Some excellent surveys of classification methods now exist,to name but a few,Ball [21]has found it necessary to give a classification of classification
...Sparck Jones [24]has provided a very clear intuitive break down of classification methods in terms of some general characteristics of the resulting classificatory system
...1 Relation between properties and classes a monothetic b polythetic 2 Relation between objects and classes a exclusive b overlapping 3 Relation between classes and classes a ordered b unordered The first category has been explored thoroughly by numerical taxonomists
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1 each one possesses a large but unspecified number of the properties in G;2 each f in G is possessed by large number of these individuals;and 3 no f in G is possessed by every individual in the aggregate
...The first sentence of Beckner s statement refers to the classical Aristotelian definition of a class,which is now termed monothetic
...To illustrate the basic distinction consider the following example Figure 3
...The distinction between overlapping and exclusive is important both from a theoretical and practical point of view
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