The sort by occurrence count means considerable reduction in processing time since the tails of the long count in document lists need not be processed. If the maximum in document frequency in the list is stored with the term, it is possible to avoid reading the list for some terms. One can regain some compression by sorting documents in the list with the same frequency by document number. Tests show no degradation in retrieval effectiveness and would permit ranked retrieval on considerably smaller machines. 749 Inter-Record Linkage Structure in a Hypertext Bibliographic Retrieval System Dietmar Wolfram Wolfram's HyperLynx system is tested on nearly 3000 NTIS document records on library and information science from 1989 to '91.
Initial entry is through author, title, and descriptor indices.
Each search term with multiple hits forms a circular list of those records which can be traversed. The distribution of the number of times a term occurs in the file is studied, as well as the distribution of co-occurrences of different breadths, and the distribution of the number of selectable terms in a record. Terms of the largest size and of the smallest size co-occur with the greatest frequency. A simple model of expected number of term co-occurrences, a simulation based on exhaustivity and term size, and a third model where the frequency of terms of a given size was assigned based upon terms per record, were implemented. The observed distribution is much more variable than those produced by the models, although matching behavior is apparent.