[Xapian-discuss] Change document relevance on user feedback

[Richard Boulton]

Benjamin Hille wrote:
> Hello,
> before I use xapian for my project, I would like if it is possible to do the
> following (Have read a lot of the archive mailing list but I am not sure I
> got it right):
> the user is show a set of result for a given query
> the user select a document and click on to say if the document is relevant.
> if it does can I update the relevance of that document for the terms used?

Yes, this is supported by Xapian.

Briefly, the API allows you to supply a relevance set to the match 
process (which is a set of documents marked as relevant).  It also 
allows a relevance set to be used to calculate a set of expansion terms 
(ie, terms which might be useful to add to the query to find documents 
similar to those marked as relevant).


http://xapian.org/search.php supports this method of feedback - each 
result has a checkbox - if you click the checkbox and then click the 
"Search" button again, the termweights will be adjusted based on the new 
information, and results will be recalculated.  For small queries, this 
often doesn't produce much direct improvement, because only the weights 
of the terms are modified, so two documents which match the same terms 
will often remain ranked in the same order, even if only one of the 
documents was relevant.

However, xapian also supports calculation of a list of suggested 
"expansion" terms, which are displayed at the top of the screen in this 
case.  These terms will also be updated based on the relevance 
information.  You can click the boxes by these terms to add them to the 
query, but an alternative implementation is to simply add such terms 
automatically to the query ("behind the scenes", so that the user 
doesn't see them), which is more limited, but may be an easier interface 
for users.

-- 
Richard