1. Lightweight Distributed Trust Propagation (daniele quercia & stephen hailes & licia capra) U C L

2. What I do...

3. Research @ ...

5. What I research...

6. Reputation Systems for Mobiles

7. Daniele Quercia Situation : People exchange digital content

8. Daniele Quercia Problem : Content overload

9. Daniele Quercia Proposal: Accept content only from reputable people

10. Daniele Quercia Take two devices… A B

11. Daniele Quercia A B Shall I accept content from B ?

12. Daniele Quercia A B A should set its initial trust for B

13. Daniele Quercia A B A should set its initial trust for B Yes, but how?

17. Conclusion: A needs a new way for propagating its trust in B

18. Conclusion: A needs a new way for propagating its trust in B But which way?

19. Our proposal

20. Daniele Quercia 1 ? A B C 2 A  B A  C C  B

21. Daniele Quercia 1 ? A B C 2 ? Put trust relationships in a new graph & label graph nodes 1 2 A  B A  C C  B

22. Daniele Quercia 1 ? A B C 2 ? Put trust relationships in a new graph & label graph nodes Define a “good” function that rates A  B f 1 2 A  B A  C C  B

23. Daniele Quercia 1 ? A B C 2 ? build_graph ( trust_relationships, A  B ) f find_f 1 2 A  B A  C C  B

24. <build_graph>

25. A B D C 3 2 1 1 2 ? A  B ? ? 2 3 1 0.5 1 M M

26. A B D C 3 2 1 1 2 ? A  B ? ? 2 3 1 0.5 1 M M What are those ?

27. Remember, we’ll define f We will see that f rates neighbouring nodes alike It’s a neighbour of A  B; therefore, it rates as A  B does ?

28. Remember, we’ll define f We will see that f rates neighbouring nodes alike It’s a neighbour of A  B; therefore, it rates as A  B does ? Find relationships that rate as A  B does

29. Remember, we’ll define f We will see that f rates neighbouring nodes alike It’s a neighbour of A  B; therefore, it rates as A  B does ?

30. 2 Types of those relationships

31. 1. The relationships with same rater ( A ) A B D C 3 2 1 1 2 As long as B and D behave alike

32. A B D C 3 2 1 1 2 2. The relationships with same rated node ( B ) As long as A and C rate alike

33. OK, 2 Types

34. Taking those relationships, one comes up with …

36. </build_graph>

37. <find_f>

38. A  C A  B A  D C  B 2 3 1 0.5 1 M M

40. More formally, …

41. We find f that minimizes that loss!

42. </find_f>

43. Daniele Quercia 1 ? A B C 2 ? build_graph f find_f 1 2 A  B A  C C  B

47. Daniele Quercia Robust?

48. Daniele Quercia Robust?

49. Daniele Quercia Fast and “ Light ”?

51. Daniele Quercia All this on …

52. Daniele Quercia All this on …

53. Daniele Quercia