#  The Smoothed and Semi-Random Possibilities of Social Choice 

 



####  calendar\_today Date and Time 

 **November 11, 2022** 

 01:00PM - 02:00PM EST 

####  pin\_drop Location 

 **https://harvard.zoom.us/j/95184948637?pwd=bXBIc2U5MEZ0QmRUb01WQ0o0SXRCdz09**  



 

 



 

 Lirong Xia (RPI) will be speaking **over Zoom** on:

 *The Smoothed and Semi-Random Possibilities of Social Choice*

 Abstract:

 Social choice studies how to aggregate agents' preferences to make a collective decision. It plays a critical role in many group decision making scenarios in human society as well as in multi-agent systems. A prominent challenge in designing desirable social choice mechanisms is the wide presence of worst-case paradoxes and impossibility theorems. While there is a large body of literature on using average-case analysis to circumvent the impossibilities, the models in previous work were criticized for being unrealistic, and technical tools for going beyond a few voting rules and a few distributions are lacking.

 We take a worst average-case approach to propose a natural, general, and more realistic semi-random model that resembles the celebrated smoothed analysis under semi-random models. We characterize the conditions and rates for the semi-random likelihood of Condorcet's paradox, the ANR impossibility theorem, and the Gibbard-Satterthwaite theorem to vanish, by representing them as unions of polyhedra and characterizing the semi-random likelihood for a Poisson Multinomial Variable to be in the polyhedra. Straightforward applications of our theorems to the Impartial Culture distribution address long-standing open questions. Our results illustrate the smoothedand semi-random possibilities of social choice, and help build a more realistic foundation of social choice that goes beyond worst cases.

 The talk is based on the following papers:

 [https://arxiv.org/abs/2006.06875](https://urldefense.proofpoint.com/v2/url?u=https-3A__arxiv.org_abs_2006.06875&d=DwMFaQ&c=WO-RGvefibhHBZq3fL85hQ&r=ZOP6tLIqLOHbdgCvrXjUlPta0tw7K_-ivqiItQhh6LQ&m=4lkICTgpE4Y4fQ5MO_jp1yIO42gPzPzxCVBLyuPzYtfu-H_g3mQEZlVOyiFWSmnX&s=6MjGmkVlfo6G3OGMp8gFthvY3IPkR-KPNYIVq5PJhzg&e=)

 [https://arxiv.org/abs/2011.03791](https://urldefense.proofpoint.com/v2/url?u=https-3A__arxiv.org_abs_2011.03791&d=DwMFaQ&c=WO-RGvefibhHBZq3fL85hQ&r=ZOP6tLIqLOHbdgCvrXjUlPta0tw7K_-ivqiItQhh6LQ&m=4lkICTgpE4Y4fQ5MO_jp1yIO42gPzPzxCVBLyuPzYtfu-H_g3mQEZlVOyiFWSmnX&s=P1R4yE7TUOmBUI2lRjxterc2Km-pEEFB4HVRN4urEbQ&e=)

 [https://arxiv.org/abs/2202.06411](https://urldefense.proofpoint.com/v2/url?u=https-3A__arxiv.org_abs_2202.06411&d=DwMFaQ&c=WO-RGvefibhHBZq3fL85hQ&r=ZOP6tLIqLOHbdgCvrXjUlPta0tw7K_-ivqiItQhh6LQ&m=4lkICTgpE4Y4fQ5MO_jp1yIO42gPzPzxCVBLyuPzYtfu-H_g3mQEZlVOyiFWSmnX&s=e4J9Po-NOFRsKxXbo9xdqRDKAQ1l-DIlEw34fkb7wck&e=)



 

 



 

 See also:- [ Fall 2022 Econ CS Seminars ](/taxonomycalendarseminar/fall-2022)
 
 

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