SP500215 On Expanding Query Vectors with Lexically Related Words chapter E. Voorhees National Institute of Standards and Technology D. K. Harman Expansion by synonyms only orig terms [OCRerr] synonyms OL 1 .1 1 .3 1 .5 1 .8 Expansion by synonyms plus all descendents orig terms a synonyms a descendents a 1 .1 .1 1 .3 .1 1 .3 .3 1 .5 .1 1 .5 .3 1 .5 .5 1 .8 .1 1 .8 .3 1 .8 .5 Expansion by synonyms plus parents and all descendents orig terms a synonyms a descendents a parents a 1 .1 .1 .1 1 .3 .1 .1 1 .3 .3 .3 1 .5 .1 .1 1 .5 .3 .1 1 .5 .3 .3 1 .5 .5 .1 1 .5 .5 .3 1 .5 .5 .5 1 .8 .1 .1 1 .8 .3 .1 1 .8 .3 .3 1 .8 .5 .1 1 .8 .5 .3 1 .8 .5 .5 Expansion by synonyms plus any directly related synset orig terms a synonyms a other a 1 .3 .1 1 .3 .3 1 .5 .1 1 .5 .3 1 .5 .5 1 .3 .5 Table 1: Combinations of expansion strategies and relation weights tested. 228