EconCS Seminar

 

Lecturer: 

Dr. Yotam Gafni (Weizmann)

Title: 

Some Positive Results for False-Name Resistance in Combinatorial Auctions & Voting Games

Abstract: 

Economic mechanism design studies how to design mechanisms that satisfy good societal properties, while considering that agents may try to game the system. An ominous form of attack is the ’False Name Attack’, where agents use multiple fake identities to interact with the system for their benefit. These attacks appear in a plethora of settings, such as combinatorial auctions, and in the formation of voting bodies. Generally, trying to mitigate false-name attacks comes at the cost of significant welfare/fairness loss. 
Our goal is to show some positive results for mechanism design in this setting, using randomized, Bayesian, and risk-averse approaches. 

More specifically, in the context of combinatorial auctions, we show that for a reasonable valuation class, and many natural distributions, the well-known Vickrey-Clarke-Groves (VCG) combinatorial auction admits a truthful Bayesian equilibrium, even when bidders may freely perform false-name attacks. We introduce a new solution concept we call “Distinguishable Safety Level”, and show that if all bidders adopt this notion of robust reasoning under uncertainty, then the outcome of the VCG auction, even when possibly not truthful, achieves optimal efficiency. In the context of voting, we show bounds on how much small parties, that can not use false-name attacks, may possibly lose from big parties using this type of manipulation. 

Location: 

Room 130, Feldman Building, Edmond J. Safra Campus.

 

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