14. A method as claimed in claim 13 , comprising: calculating, in respect of each document, a probability distribution indicative of the frequency of occurrence of each term in the document; comparing the respective probability distribution of each document with each probability distribution selected as a cluster attractor; and assigning each document to at least one cluster depending on the similarity between the compared probability distributions.
14. A method as claimed in claim 13 , comprising: calculating, in respect of each document, a probability distribution indicative of the frequency of occurrence of each term in the document; comparing the respective probability distribution of each document with each probability distribution selected as a cluster attractor; and assigning each document to at least one cluster depending on the similarity between the compared probability distributions. 15. A method as claimed in claim 14 , comprising organizing the documents within each cluster by: assigning a respective weight to each document, the value of the weight depending on the similarity between the probability distribution of the document and the probability distribution of the cluster attractor; comparing the respective probability distribution of each document in the cluster with the probability distribution of each other document in the cluster; assigning a respective weight to each pair of compared documents, the value of the weight depending on the similarity between the compared respective probability distributions of each document of the pair; calculating a minimum spanning tree for the cluster based on the respective calculated weights.