1. Relevance Feedback and Query Modification
Discussion Class 9
Relevance Feedback and Query Modification

2. Discussion Classes Format: Question
Ask a member of the class to answer
Provide opportunity for others to comment
When answering:
Give your name. Make sure that the TA hears it.
Stand up
Speak clearly so that all the class can hear

3. Question 1: Terminology
Define the following terms:
(a) Relevance feedback
(b) Query expansion
(c) Term reweighing
(d) Term-term clustering

4. Question 2: Rocchio and Ide dec-hi
(a) Contrast the Rocchio algorithm:
with the Ide dec-hi algorithm:
(b) For the Rocchio algorithm, suggested values for the parameters are  = 1,  = 0.75,  = How does this relate to the Ide dec-hi?
Q1 =  Q0 +  Ri -  Si 
i =1 n1 1 n2 
i =1 n1
Q1 = Q Ri - S

5. Question 2: (notation) Q0 = vector for the initial query
Q1 = vector for the modified query
Ri = vector for relevant document i
Si = vector for non-relevant document i
S = vector for the top non-relevant document
n1 = number of relevant documents
n2 = number of non-relevant documents

6. Question 3: Use of relevance feedback and query expansion
(a) What characteristics of a document collection are necessary for effective use of relevance feedback and query expansion?
(b) When do users find relevance feedback helpful?

7. Question 4: Implementation
(a) What are the challenge(s) in implementing efficient systems for relevance feedback?
(b) The author discusses two approaches for overcoming these challenges. What are they?

8. Question 5: Boolean queries
(a) What are the difficulties in implementing relevance feedback in Boolean systems?
(b) What are some of the possible approaches for overcoming these difficulties?

9. Question 6: Use of relevance feedback and query expansion
In a recent article, Bruce Croft wrote that " traditional feedback techniques can be unpredictable in operational settings." Why do you think that this occurs?