SP500215 Appendix B: System Features Appendix National Institute of Standards and Technology D. K. Harman ilL SEARCHING 32150 cpu seconds per query if no query expansion (dortVI). 1196/50 cpu seconds per query if expand by 20 terms (dortpl). [OCRerr]/50 (i.e., 16.5) seconds for each query for crnlV2. 8568/50 seconds for each query for crnl12 (involves re-indexing from scratch the top 1750 docs for each que! [OCRerr]h indexed local component against the query). 3273/50 seconds for each query for crnlRl on a Sparc 1 with 12MB of memory (all other work was done C [OCRerr] Mbytes). 2928/50 seconds for each query for crnlCl on a Sparc 1 with 12MB of memory. robabalistic searching based on linked dependence assumption and logistic regression. n equation derived by logistic regression was used to estimate a probability of relevance for each query and document. ince our experiments were done on a time-shared system, we present here both the mean cpu time of seven runs of each experiment, as an estimate of search a realistic multi-user environment; and, the minimum cpu time of the seven runs, as an upper bound on search and sorting time for a single-user system. I ere using, we were unable to separate search and sorting time and therefore, present the total cpu time for producing the sorted lists of 1000 retrieved ite ur timing results are reported as follows: first for the routing topics, using all 50 topics, giving total cpu time for the experiment (mean and minimum) and me )u time per topic (our rutcombx run); then for the adhoc topics, in which we used only 25 topics, the same figures (our rutcombl run). For the rutfined run [OCRerr]h having five individual searches, the resulting lists being subsequently combined), we estimate the upper bound of total time as being five times the minimu r runcombi, plus the time required for combining the lists. These are presented as total cpu time for the experiment, and mean cpu time per topic. itcombx Total: 981.55 (973.55) Per Topic: 19.631 (19.471) itcombl Total: 1226.225 (1208.325) Per Topic: 49.049 (48.333) itmedf Total: 5799.96 + 373.2 = 6173.16 Per Topic 241.665+15.55 = 257.215 3£ cpu seconds on average for routing queries against test documents (691 cpu seconds for 50 queries). 17A cpu seconds on average for unexpanded adhi `cuments on disks 1 & 2 (869 cpu seconds for 50 queries). 19.5 cpu seconds on average for expanded adhoc queries versus documents on disk 1 & 2 (974 q ~eries). ot applicable; list of top 1000 maintained during search. cpu second per query term on per gigabyte. Queries averaged about 45 terms each. pproximately 4 - 7 minutes per topic for combination runs (multiple queries) per topic, for a given collection. ombination of results from both pnorm (flizzy logic) and vector (vector space model) queries.