9. A method as in claim 7 wherein step (vi) comprises selecting the document for retrieval on the basis of the least degree of dissimilarity.
9. A method as in claim 7 wherein step (vi) comprises selecting the document for retrieval on the basis of the least degree of dissimilarity. 14. A method as in claim 9, wherein the weight modifying function comprises multiplying each weight (Wi) by a respective weight factor (1+ki), where ki is a function of the contribution that the respective weighted comparison result makes to the dissimilarity measure, and the difference between the initial comparison result and the further comparison result.