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Approximations and Truthfulness: The Case of Multi-Unit Auctions

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Approximations and Truthfulness: The Case of Multi-Unit Auctions. Shahar Dobzinski Joint work with Noam Nisan and with Shaddin Dughmi. Auctions. Clean Air Auction. 1990’s: The US government decided to decrease the atmospheric levels of sulfur dioxide. - PowerPoint PPT Presentation

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Auctions

Clean Air Auction

Definition of Multi-Unit Auctions

Can we obtain an algorithm that is fast, truthful and approximates the welfare

well?

Related Work

Theorem: There exists a truthful poly time randomized (1-)-approximation mechanism.

Theorem: There exists a poly time deterministic truthful ½-approximation mechanism.

Maximal in Range: limit the range and fully optimize over the restricted range.

The mechanism: (1)Split the items into n2 equi-sized bundles each of size m/n2.(2)Allocate these bundles optimally.

Theorem: Every maximal-in-range (½+)-approx algorithm requires at least m queries to the black boxes.

Proving Impossibilities:Characterize and Optimize

+ =

What’s Next?

Theorem: there exists a (1-)-approximation mechanism that is truthful in expectation.

The AlgorithmSome valuation function

Items

Value

Correctness

Summary

Open Questions

Basic Requirements from Auctions

This talk: auction design via multi-unit auctions.

Modern Auctions I: eBay

Modern Auctions II: Sponsored Search