1. User Modelling and Groups Where? –CSCW –CSCL –Collaborative filtering –P2P, ubiquitous computing What? –Explicit group model –Interacting individual models –Interacting UM fragments Why? –Improve individual adaptation –Facilitate collaboration –Facilitate negotiation –Motivate participation –Models represent users (in MAS) How? – Capturing parameters of group activity – Reconsiliating individ. models with group model – No group model; interaction of individ. models Jameson, Lock, Winter, Masthoff Gaudioso, Goodman Sun, Kaminka Tang, Zhu Jameson, Winter, Tang Goodman, Gaudioso, Masthoff Jameson, Gaudioso, Masthof, Sun, Lock, Kaminka Kaminka, Tang & McCalla, Zhu Goodman, Gaudioso, Lock Jameson, Masthoff Sun Jameson Winter, Gaudioso, GoodmanT ang, Zhu Jameson, Lock, Masthoff Sun, Kaminka,

2. My vision: Loose groups and virtual communities Why? –History

3. Ensuring Quality of Service in P2P File Sharing through User and Relationship Modelling Lingling Sun, Yamini Upadrashta, Julita Vassileva MADMUC Lab, Computer Science Department, University of Saskatchewan

4. Loose Groups and Virtual Communities Ubiquitous: P2P applications, newsgroups, chatrooms, bloggers Users are often anonymous No explicit common goal, no assigned roles; goals and roles emerge Motivation to participate and contribute is crucial

5. COMTELLA A P2P (Gnutella based) system for file sharing and service –users share academic papers, code snippets, help non-centralized digital library for a research group / class motivation and community-building Christopher Cox NSERC Summer 2002 project Helen Bretzke CRA-W and NSERC Summer’ 2002 project Lingling Sun undergraduate project Yamini Upadrashta Graduate student

6. Modelling relationships between pairs of users based on positive experience Every peer keeps a list of friends in each area of interest If a peer appears in many “friends lists”, s/he is important for this community Our approach

7. Relationships –Not necessarily symmetrical! –Reinforcement learning based on history of interactions between two peers –Each relationship has strength, balance.

8. Adaptation Rewarding peers who are friends of many other peers with better QoS –Transfers not interrupted, higher badwidht, priority in queues Having many good friends “pays” –Faster search, more relevant documents

9. Evaluation results - simulation Figure 1: Graph comparing the round trip time obtained for queries without a friends’ list with the round trip time for queries with friends’ list

10. Evaluation results – user experiment

11. Conclusion The simulation results show that peers obtain results faster when searching for files in categories for which they have friends The user evaluation still underway