Re "reducing the set of question/answer pair to consider" below - I would expect that using synonyms either in the index or in the reformed query would (annoyingly) increase the number of potential matches or is there something I'm missing.
Interesting that this topic just came up as I wanted to experiment w/ the same thing. My first stab at an public domain synonym list, the "moby" list, didn't seem to have synonyms however. I believe another poster mentioned WordNet so I'll try that. I'd really like it if it was possibly to automatically determine synonyms - maybe something similar to Latent Semantic Analysis - but such things seem kinda hard to code up... -----Original Message----- From: Aaron Galea [mailto:agale@;nextgen.net.mt] Sent: Sunday, November 10, 2002 4:18 PM To: Lucene Users List; [EMAIL PROTECTED] Subject: Re: Indexing synonyms Thanks for all your replies, Well I will start of with an idea of what I am trying to achieve. I am building a question answer system and one of its modules is an FAQ Module. Since the QA system is concerned with education, users can concentrate their question on a particular subject reducing the set of question/answer pair to consider. Since there is this hierarchical indexing the index files are not that big so I can store synonyms for each word in a question in the index. Query expansion will solve the problem and eliminating the need to store synonyms in the index but this will slow things as there is no depth limit to consider for term expansion. It is not my intension to build something similar to the FAQFinder system but I want to further reduce the subset of questions to consider on which a question reformulation algorithm would be applied. Therefore the idea is get an faq file dealing with one education subject, index all of its questions and expand each term in the question. Using lucene I will retrieve the questions that are likely to be similar to a user question, select say the top 5 and apply a query reformulation algorithm. If this succeeds fine and I return the answer to user, otherwise submit the question to an answer extraction module. The most important thing is speed so putting term expansion in the index hopefully should improve things. Obviously problems arise with this method as there is no word sense disambiguation but the query reformulation algorithm will solve this. However it is slow so I must reduce the number of questions it is applied on. It is a tradeoff!!! Well I managed to solve this by overriding the next() method and when it gets to an EOS I start returning the new expanded terms that I accumulated in a list. Thanks everyone for your reply!!!! Aaron NB : And yep I am a Malteser Otis ! :) ----- Original Message ----- From: "Alex Murzaku" <[EMAIL PROTECTED]> To: "'Lucene Users List'" <[EMAIL PROTECTED]> Sent: Monday, November 11, 2002 12:17 AM Subject: RE: Indexing synonyms > You could also do something with org.apache.lucene.analyzer.Token which > includes the following self-explanatory note: > > /** Set the position increment. This determines the position of this > token > * relative to the previous Token in a {@link TokenStream}, used in > phrase > * searching. > * > * <p>The default value is one. > * > * <p>Some common uses for this are:<ul> > * > * <li>Set it to zero to put multiple terms in the same position. > This is > * useful if, e.g., a word has multiple stems. Searches for phrases > * including either stem will match. In this case, all but the first > stem's > * increment should be set to zero: the increment of the first > instance > * should be one. Repeating a token with an increment of zero can > also be > * used to boost the scores of matches on that token. > * > * <li>Set it to values greater than one to inhibit exact phrase > matches. > * If, for example, one does not want phrases to match across removed > stop > * words, then one could build a stop word filter that removes stop > words and > * also sets the increment to the number of stop words removed before > each > * non-stop word. Then exact phrase queries will only match when the > terms > * occur with no intervening stop words. > * > * </ul> > * @see TermPositions > */ > public void setPositionIncrement(int positionIncrement) { > if (positionIncrement < 0) > throw new IllegalArgumentException > ("Increment must be positive: " + positionIncrement); > this.positionIncrement = positionIncrement; > } > > > -- > Alex Murzaku > ___________________________________________ > alex(at)lissus.com http://www.lissus.com > > -----Original Message----- > From: Otis Gospodnetic [mailto:otis_gospodnetic@;yahoo.com] > Sent: Sunday, November 10, 2002 1:30 PM > To: Lucene Users List > Subject: Re: Indexing synonyms > > > .mt? Malta? That's rare! :) > > A person called Clemens Marschner just submitted diffs for query > rewriting to lucene-dev list 1-2 weeks ago. The diffs are not in CVS > yet, and they are a bit old now becase the code they were made against > has changed since they were made. You could either try applying them > yourself, of waiting until they get applied and then you could get a > nightly build. > > Otis > > --- Aaron Galea <[EMAIL PROTECTED]> wrote: > > Hi everyone, > > > > I need to create a filter that extends a tokenfilter whose purpose is > > to generate some synonyms for words in the document using Wordnet. > > Well searching for synonyms using wordnet is not that problematic but > > I need to add the synonym words to Lucene tokenstream before they are > > passed for indexing. However TokenStream class does not support any > > add method. Did anyone ever needed to do this? Can someone suggest an > > alternative of how to add some synonym words to the index? > > > > Thanks > > Aaron > > > > > __________________________________________________ > Do you Yahoo!? > U2 on LAUNCH - Exclusive greatest hits videos http://launch.yahoo.com/u2 > > -- > To unsubscribe, e-mail: > <mailto:lucene-user-unsubscribe@;jakarta.apache.org> > For additional commands, e-mail: > <mailto:lucene-user-help@;jakarta.apache.org> > > > -- > To unsubscribe, e-mail: <mailto:lucene-user-unsubscribe@;jakarta.apache.org> > For additional commands, e-mail: <mailto:lucene-user-help@;jakarta.apache.org> > > --- > [This E-mail was scanned for spam and viruses by NextGen.net.] > > > --- [This E-mail was scanned for spam and viruses by NextGen.net.] -- To unsubscribe, e-mail: <mailto:lucene-user-unsubscribe@;jakarta.apache.org> For additional commands, e-mail: <mailto:lucene-user-help@;jakarta.apache.org> -- To unsubscribe, e-mail: <mailto:lucene-user-unsubscribe@;jakarta.apache.org> For additional commands, e-mail: <mailto:lucene-user-help@;jakarta.apache.org>
