Hi, I have tried to study to lucene scoring in the default similarity. Can anyone explain me, how this similarity was designed? I have read a lot of IR literature, but I have never seen an equation like the one used in lucene. Why is this better then the normal cosine-measure?
Thanks, Klaus -----Ursprüngliche Nachricht----- Von: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Im Auftrag von Chris Hostetter Gesendet: Mittwoch, 11. Januar 2006 20:55 An: java-user@lucene.apache.org Betreff: Re: Boolean Query : BooleanQuery query = new BooleanQuery(); : for(Term t: terms) : { : query = new TermQuery(t); : query.add(t, false, false); // ist his wrong? : } : : If I construct the query as a string like "A a OR B b OR C" I get much more : results. I assume that the Boolean query uses an AND operator. How can I : change that. The "false, false" on when you add the subclauses should be doing the "OR" behavior, but more then likely the problem you are running into has to do with the analyzer being used by your QueryParser when it parses your string -- when you build the query up by hand, no analyzer is used, so if the analyzer used at indexing time did any lowercasing or steming you'll miss a lot of matches. a quick thing you should try is comparing the toString from each of the queries you are comparing (the one QueryParser built, and the one you built by hand). You should also look at this wiki entry, and pick up a copy of Lucene in Action and read chapter 4. : And I'm wondering what happens if I boost a TermQuery with a value smaller : then one. I'm asking because I would like to boost each TermQuery with the : td*idf Value of the term in the original document. From my point of view, : this should lead to a better precision, but on the first looks the results : are worse. Before you try this, make sure you understand the existing score claculation ... look a the explain info for each document against your query and see what it's already doing. -Hoss --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
