Information filtering

information retrieval.... collaborative filtering.....

1. IR Presentation Collaborative Filtering Presented by- Diksha R. Gupta Roll no.:- 7

2. Information Filtering

3. Contents Information Filtering – Content-based filtering and Collaborative filtering Content-based Filtering A content-based filtering model based on multiple criteria evaluation Collaborative Filtering

4. Information Filtering Information Filtering is the process of monitoring large amounts of dynamically generated information and pushing to a user the subset of information likely to be of her/his interest (based on her/his information needs ).

5. Information Filtering(Cont…)

6. Information Filtering(cont…)

7. Information Filtering: main categories

8. Recommender Systems Systems for recommending items (e.g. books, movies, CD’s, web pages, newsgroup messages) to users based on examples of their preferences. Many on-line stores provide recommendations (e.g. Amazon, CDNow ). Recommenders have been shown to substantially increase sales at on-line stores. There are two basic approaches to recommending: Collaborative Filtering (a.k.a. social filtering) Content-based

9. Content-based Filtering

10. Collaborative Filtering (Social Filtering)

11. Collaborative Filtering

12. Collaborative Filtering(cont..)

13. Collaborative Filtering

14. Collaborative Filtering(Cont..) Methods for collaborative recommendations can be grouped into two general classes: – Memory-based (or heuristic-based) – Model-based.

15. Collaborative Filtering(Cont..)

16. Collaborative Filtering(Cont..) Model-based methods use the collection of ratings to learn a model, which is then used to make rating predictions . probabilistic models Markov decision processes based on machine learning techniques

17. Hybrid Methods 1 . implementing collaborative and content-based methods separately and combining their predictions 2. incorporating some content-based characteristics into a collaborative approach 3. incorporating some collaborative characteristics into a content-based approach 4. constructing a general unifying model that incorporates both content-based and collaborative characteristics .

18. Rocchio ’ illustrated : centroid of relevant documents

19. Rocchio ’ illustrated does not separate relevant / nonrelevant.

20. Rocchio ’ illustrated centroid of nonrelevant documents.

21. Rocchio ’ illustrated - difference vector

22. Rocchio ’ illustrated Add difference vector to …

23. Rocchio ’ illustrated … to get

24. Rocchio ’ illustrated separates relevant / nonrelevant perfectly.

25. Rocchio ’ illustrated separates relevant / nonrelevant perfectly.

26. Rocchio Formula 4 8 1 2 4 1 2 1 1 4 -1 6 3 7 -3 4 8 2 4 8 2 8 4 4 16 Original profile Positive Feedback Negative feedback (+) (-) New profile

27. T HANK ‘S