2011 at 5:04 PM, Burton-West, Tom <tburt...@umich.edu> wrote: > Hello, > > I'm having trouble understanding the relationship of the word "tie" and > "tiebreaker" to the explanation of this parameter on the wiki. > What two (or more things) are in a tie? and how does the number in the range > from 0 to 1 break the tie?
Perhaps the parameter could have had a better name. It's essentially max(score of matching clauses) + tie * (score of matching clauses that are not the max) So it can be used and thought of as a tiebreak only in the sense that if two docs match a clause (with essentially the same score), then a small tie value will act as a tiebreaker *if* one of those docs also matches some other fields. /** * A query that generates the union of documents produced by its subqueries, and that scores each document with the maximum * score for that document as produced by any subquery, plus a tie breaking increment for any additional matching subqueries. * This is useful when searching for a word in multiple fields with different boost factors (so that the fields cannot be * combined equivalently into a single search field). We want the primary score to be the one associated with the highest boost, * not the sum of the field scores (as BooleanQuery would give). * If the query is "albino elephant" this ensures that "albino" matching one field and "elephant" matching * another gets a higher score than "albino" matching both fields. * To get this result, use both BooleanQuery and DisjunctionMaxQuery: for each term a DisjunctionMaxQuery searches for it in * each field, while the set of these DisjunctionMaxQuery's is combined into a BooleanQuery. * The tie breaker capability allows results that include the same term in multiple fields to be judged better than results that * include this term in only the best of those multiple fields, without confusing this with the better case of two different terms * in the multiple fields. */ -Yonik http://www.lucenerevolution.org -- Lucene/Solr User Conference, May 25-26, San FranciscoOn Thu, Apr 14,
