IRS13 Thesaurus, Phrase and Hierarchy Dictionaries chapter E. M. Keen Harvard University Gerard Salton Use, reproduction, or publication, in whole or in part, is permitted for any purpose of the United States Government. 0 STEM THESAURUS-I (OLD Q.S.) ½ 0 STEM 0½ THESAURUS-2 (NEW Q.Sb) ½ 0 STEM 0½A THESAURUS-3 (HARI ½ C SION PREC SION PREC SION .0 1.0 - 1.0 - .8 0.6 0.6 .6 - 0.6 - 0.6 - 4 - 0 OA - OA - .2 - 0.2 - 0.2 - I I I I i I I I i I 0 Ol OA 0.6 0.8 I.0[OCRerr] RECALL 0 ilililil I 1PrrAII 0.2 0*4 0.6 0.8 1.0 [OCRerr] I I I I I I I I I I r'r 0.2 0.4 0.6 OB I.[OCRerr] Comparison 8 Comparison 9 Comparison 10 Cran-1, Abstracts, 42 Requests Cran-l, Abstracts, 42 Requests Cran-1, Abstracts, 42 Request Performance Curves Comparing Stem and Thesaurus Dictionaries on the Cran-l Collection Fig. 9