Comments on "a comparison of concatenated and superimposed code word surrogate files for very large data/knowledge bases"

Direct searching and retrieval from a very large data/knowledge base systemare very time-consuming. The use of surrogate files, or description files, based on indexing techniques can speed up the process of information retrieval. In a recent paper [1], two indexing techniques, Concatenated and Superimposed Code Words, CCW and SCW respectively, were suggested for handling very large knowledge base systems with file size approaching Gigabytes. The space requirements and the query response times of surrogate files based on the two indexing techniques were estimated and compared. From the comparison, the CCW indexing technique was claimed to be better: it required relatively less storage and provided a faster response time. In this paper, the analysis leading to the claim is re-examined. Furthermore, it is shown that the comparison was unfairly conducted and it was biased against SCW. Contrary to the claim, SCW surrogate files do not necessarily require more storage than CCW surrogate files. In the first section, the analysis in [1] is briefly summarised. A revised analysis is described in Section 2. Finally, conclusions are given in Section 3. © 1989.