A recursive algorithm for generating SLIC index entries

Combination indexing is a method of ordering a set of terms or keywords on the syntagmatic axis rather than the paradigmatic axis. All terms applied to the document by the indexer are listed in all possible combinations to produce the index entries, and therefore the user should be able to search the index with no more knowledge of its structure beyond alphabetization. The disadvantage of combination indexing is the large number of entries produced. For n keywords, n! entries are produced. With a very few terms in each string this is not a serious problem, but when several terms are included in a string the number of entries soon reaches excessive proportions. Five terms would produce one hundred and twenty entries; seven terms, five thousand and forty entries.