Title:    Thresholds for Detection                                 Page 1 of  
Date Prepared: October 17, 1995         
	       April 3, 1996

Priority: Routine
Document Affected : Design (1.52)
Paragraphs Affected:
References: 

Change Required:
---------------
	Modify RetrieveDocuments() DocumentCollectionIndex [DCI] and 
	AddQuery() for QueryCollectionIndex [QCI] to accept an
	additional float argument indicating the user's "relevance
	threshold" for retrieved or matched Documents. 

	The threshold will be represented by a real number in the range
	[0,1.0].  A threshold of 0.0 indicates that all matching
	Documents will be returned.  


Specific Recommendation:
-----------------------
(add text) Section 1.2

	Each component has a value, which may be....

		* a float (a real number)


(modify operation) Section 7.1.4  Document and Query Indexes

     DocumentCollectionIndex 
     ....

     RetrieveDocuments(sequence of DocumentCollectionIndex, 
                       RetrievalQuery,
                       NumberToRetrieve : integer,
                       Threshold : float):  Collection or nil

         returns a Collection of Documents (of maximal length
	 NumberToRetrieve) which are most closely related to the
	 DetectionNeed from which the RetrievalQuery is derived.
         All returned Documents will have a relevance rating above the
         user-specified Threshold.

	 The threshold will be a value in the range [0.0, 1.0].  A
	 threshold of 0.0 indicates that all matching Documents up to
	 a maximum of NumberToRetrieve will be returned.   

	 If no Documents match the RetrievalQuery argument, nil will
	 be returned.

Title:    Thresholds for Detection                                 Page 2 of  


(modify operation) Section 7.1.4  Document and Query Indexes

     QueryCollectionIndex 
      ....

     
      AddQuery(QueryCollectionIndex,
               RoutingQuery,
               Threshold : float)


	  Adds RoutingQuery to the QueryCollectionIndex.
	  If a RoutingQuery in the QueryCollectionIndex has a
	  DetectionNeed component matching the DetectionNeed component
	  of the RoutingQuery argument, the existing RoutingQuery is
	  replaced by the RoutingQuery argument.

	  The Threshold argument is used to control the Documents the
	  RoutingQuery matches during RetrieveQueries() operations.
	  The RoutingQuery will match Documents if the relevance
	  rating is above the specified relevance rating Threshold.  A
	  threshold of 0.0 indicates that the DetectionNeed the
	  RoutingQuery was derived from will be returned from the
	  RetrieveQueries() operation for all matching Documents.



Reason for Proposed Change:
--------------------------

	In the current TIPSTER Architecture, a user can query a
	DocumentCollectionIndex(DCI) to receive a Collection of
	Documents relevant to the user's information need
	(DetectionNeed).  The user controls the retrieval of Documents
	only by specifying a maximum number of Documents they will
	receive.  However, a user may wish to receive Documents above
	a certain "relevance threshold" in the returned Collection.   
    
        The threshold limitation also occurs with the
        QueryCollectionIndex.  A user can use the AddQuery() operation
        to add their RoutingQuery to a QueryCollectionIndex (QCI).
        Once added to the QCI, the RoutingQuery will be used to
        determine whether an incoming Document matches the user's
        information need.  Again, a user has no way of limiting the 
        range of Documents which may match their information
        need. A user may wish to only have their RoutingQuery match a
        Document only if the Document's relevance to the query is
        above a certain "relevance threshold". 

	Adding a relevance threshold to the operations RetrieveDocuments() 
	for DocumentCollectionIndex [DCI] and AddQuery() for
	QueryCollectionIndex [QCI] offers users more flexibility.
	This type of filtering can be done currently outside the scope
	of the architecture, but doing so prevents plug and play of 
	Detection systems.  By adding the threshold to the Tipster API,
	plug & play of Detection modules is enabled.

Title:    Thresholds for Detection                                 Page 3 of  


	The "relevance threshold" shall be general so that all
	TIPSTER Detection systems shall be able to interpret the
	threshold in a manner appropriate to their system.  The
	threshold will be represented by an float on a scale of
	[0,1.0].  A threshold of 0.0 indicates that all matching
	Documents will be returned.  


Applications Affected:

Change Requested By:
    Organization:  	University of Massachusetts
    Name:  		Kathleen S. DiBella
    Phone Number:   	(413)545-9781
    Date: