1. Efficient Voting via the Top-k Elicitation Scheme: A Probabilistic Approach Joel Oren, University of Toronto Joint work with Yuval Filmus, Institute of Advanced Study 1

2. Motivation Common theme: communication-efficient group decision- making. How to pick the single “best” item/candidate, without extracting too much information from the customers/committee members. Hiring committees: members can’t rank all of the candidates. Too many candidates. Committee members may only be familiar with just subsets of candidates in their own fields. 2

3. The Basic Setting 3 1.A canonical task: select the “best” outcome. 2.What is the information need for doing so. 1.Social choice: methods for aggregating preferences. 2.Efficient preference elicitation.

4. Basic Definitions 4 Borda Harmonic Geometric

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6. Previous Work 6

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8. Three Distributional Models (and high-level Results) 8

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10. Empirical Results for the three algorithms 10 FairCutoff overlaps with Opt

11. A Threshold Theorem for PSRs 11

12. Applications 12

13. Proof Sketch – Order Statistics of Correlated RVs 13

14. Proof Sketch (continued) 14

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16. The Adversarial Model 16

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18. Conclusions & Future Directions 18 Scoring rule LBUB Borda Harmonic Geometric Copeland

19. Contact: oren@cs.toronto.edu Homepage: www.cs.toronto.edu/~oren oren@cs.toronto.edu Thank you! 19