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Unformatted text preview: t their name since they form a sequence of groupings or clusters that
can be represented in a hierarchy of clusters. This hierarchy can be obtained
either in a top-down or bottom-up fashion. Top-down means that we start with
one cluster that contains all documents. This cluster is stepwise reﬁned by
splitting it iteratively into sub-clusters. One speaks in this case also of the so
called "divisive" algorithm. The bottom-up or "agglomerative" procedures start
by considering every document as individual cluster. Then the most similar
clusters are iteratively merged, until all documents are contained in one single
cluster. In practice the divisive procedure is almost of no importance due to its
generally bad results. Therefore, only the agglomerative algorithm is outlined
in the following.
The agglomerative procedure considers initially each document d of the the
whole document set D as an individual cluster. It is the ﬁrst cluster solution. It is
assumed that each docume...
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This note was uploaded on 06/19/2011 for the course IT 2258 taught by Professor Aymenali during the Summer '11 term at Abu Dhabi University.
- Summer '11