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Indri Query Retrieval

QueryEnvironment Parameters

Retrieval Parameters

memory

an integer value specifying the number of bytes to use for the query retrieval process. The value can include a scaling factor by adding a suffix. Valid values are (case insensitive) K = 1000, M = 1000000, G = 1000000000. So 100M would be equivalent to 100000000. The value should contain only decimal digits and the optional suffix. Specified as <memory>100M</memory> in the parameter file and as -memory=100M on the command line.

index

path to an Indri Repository. Specified as <index>/path/to/repository</index> in the parameter file and as -index=/path/to/repository on the command line. This element can be specified multiple times to combine Repositories.

server

hostname of a host running an Indri server (Indrid). Specified as <server>hostname</server> in the parameter file and as -server=hostname on the command line. The hostname can include an optional port number to connect to, using the form hostname:portnum. This element can be specified multiple times to combine servers.

count

an integer value specifying the maximum number of results to return for a given query. Specified as <count>number</count> in the parameter file and as -count=number on the command line.

rule

specifies the smoothing rule (TermScoreFunction) to apply. Format of the rule is:

( key ":" value ) [ "," key ":" value ]*

Here's an example rule in command line format:

-rule=method:linear,collectionLambda:0.2,field:title

and in parameter file format:
<rule>method:linear,collectionLambda:0.2,field:title</rule>

This corresponds to Jelinek-Mercer smoothing with background lambda equal to 0.2, only for items in a title field.

If nothing is listed for a key, all values are assumed. So, a rule that does not specify a field matches all fields. This makes -rule=method:linear,collectionLambda:0.2 a valid rule.

Valid keys:

method

smoothing method (text)

field

field to apply this rule to

operator &nbsp;

type of item in query to apply to { term, window }

Valid methods:

dirichlet

(also 'd', 'dir') (default mu=2500)

jelinek-mercer

(also 'jm', 'linear') (default collectionLambda=0.4, documentLambda=0.0), collectionLambda is also known as just "lambda", either will work

twostage

(also 'two-stage', 'two') (default mu=2500, lambda=0.4)

If the rule doesn't parse correctly, the default is Dirichlet, mu=2500.

stopper

a complex element containing one or more subelements named word, specifying the stopword list to use. Specified as <stopper><word>stopword</word></stopper> and as -stopper.word=stopword on the command line. This is an optional parameter with the default of no stopping.

Formatting Parameters

queryOffset

an integer value specifying one less than the starting query number, eg 150 for TREC formatted output. Specified as <queryOffset>number</queryOffset> in the parameter file and as -queryOffset=number on the command line.

runID

a string specifying the id for a query run, used in TREC scorable output. Specified as <runID>someID</runID> in the parameter file and as -runID=someID on the command line.

trecFormat

the symbol true to produce TREC scorable output, otherwise the symbol false. Specified as <trecFormat>true</trecFormat> in the parameter file and as -trecFormat=true on the command line. Note that 0 can be used for false, and 1 can be used for true.

Pseudo-Relevance Feedback Parameters

fbDocs

an integer specifying the number of documents to use for feedback. Specified as <fbDocs>number</fbDocs> in the parameter file and as -fbDocs=number on the command line.

fbTerms

an integer specifying the number of terms to use for feedback. Specified as <fbTerms>number</fbTerms> in the parameter file and as -fbTerms=number on the command line.

fbMu

a floating point value specifying the value of mu to use for feedback. [NB: document the feedback formulae]. Specified as <fbMu>number</fbMu> in the parameter file and as -fbMu=number on the command line.

fbOrigWeight

a floating point value in the range [0.0..1.0] specifying the weight for the original query in the expanded query. Specified as <fbOrigWeight>number</fbOrigWeight> in the parameter file and as -fbOrigWeight=number on the command line.

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