Feedback is implemented as a WSUM of the original query combined with terms selected from the feedback documents based on belief score. The expanded query has the form:
#wsum( (1 - a) <original query> a*w1 t1 a*w2 t2 ... a*wN tN )
where a is the value of the parameter
Scoring is either done over a working set of documents (essentially re-ranking), or over the whole collection. This is indicated by the parameter "useWorkingSet". When "useWorkingSet" has either a non-zero (integer) value or the value
true, scoring will be on a working set specified in a file given by "workingSetFile". The file should have three columns. The first is the query id; the second the document id; and the last a numerical value, which is ignored. By default, scoring is on the whole collection.
The parameters are:
index: The complete name of the index table-of-content file for the database index. This must be a positional index (currently KeyfileIncIndex).
textQuery: the query text stream parsed by ParseInQuery
resultFile: the result file
resultFormat: whether the result format should be of the TREC format (i.e., six-column) or just a simple three-column format
<queryID, docID, score>. String value, either
trecfor TREC format or
3colfor three column format. The integer values, zero for non-TREC format, and non-zero for TREC format used in previous versions of lemur are accepted. Default: TREC format.
resultCount: the number of documents to return as result for each query
defaultBelief: The default belief for a document: Default=0.4
feedbackDocCount: the number of docs to use for pseudo-feedback (0 means no-feedback)
feedbackTermCount: the number of terms to add to a query when doing feedback.
feedbackPosCoeff: the coefficient for positive terms in the expanded query.
Generated on Tue Jun 15 11:02:58 2010 for Lemur by 1.3.4