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Making Decisions Based on the Preferences of Multiple Agents

Making Decisions Based on the Preferences of Multiple Agents. Adviser : Judy Chuan-Chuan Li n Speaker : Sheng-Yang Chen(01756001) Sheng - Shiung Yang(01756002) Date : 2012 /11/12. COMMUNICATIONS OF THE ACM, MARCH 2010, VOL 53, NO.3 BY VINCENT CONITZER. Outline. Introduction

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Making Decisions Based on the Preferences of Multiple Agents

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  1. Making Decisions Based on the Preferences of Multiple Agents Adviser : Judy Chuan-Chuan Lin Speaker : Sheng-Yang Chen(01756001) Sheng-ShiungYang(01756002) Date : 2012/11/12 COMMUNICATIONS OF THE ACM, MARCH 2010, VOL 53, NO.3 BY VINCENT CONITZER

  2. Outline • Introduction • Settings without Payments • Voting and rank aggregation(投票和排序融合) • Allocating tasks and resources(分配任務和資源) • Kidney exchanges(腎臟移植) • Settings with Payments • Auctions and Exchanges • Combinatorial Auctions • Charitable Giving • Prediction Market • Conclusion

  3. Introduction People often must reach a joint decision even though they have conflicting preferences over the alternatives. • Computer networks provide a new platform for communicating preferences. • Within computer science, there is a growing number of settings where a decision must be made based on the conflicting preferences of multiple parties • Greater computing power and better algorithms, as well as a more computational mind-set in the general public, have made it possible to run computationally demanding protocols that lead to much better outcomes. • The paradigms of computer science give a different and useful perspective on some of the classic problems in economics and related disciplines.

  4. Settings without Payments • Voting and rank aggregation(投票和排序聚合) • Allocating tasks and resources(分配任務和資源) • Kidney exchanges(腎臟移植)

  5. Voting and rank aggregation • Plurality voting (簡單多數決制) :在簡單多數決制下，無論多少人參加選舉，以每人得票多少為準，得票最高的候選人當選。 例如：如果一群人決定一起去吃飯，其中一人可能更喜歡美國食物，再來是巴西食物及中國食物。此人的票可以表示為A> B> C。 • Anti-plurality voting(反簡單多數決制) : 排名最後得到0分，排名第一的得到一分。 3.Borda rule (博爾達計分法)選民依他們對投票選項喜好的程度，將候選 人從上到下排列，排列在越高位置的選項， 得分越高。

  6. Voting and rank aggregation • Kemeny rule • The Kemeny–Young method is a voting system that uses preferential ballots and pairwise comparison counts to identify the most popular choices in an election.( source from Wikipedia) • CP-nets(Conditional preference networks) • CP-nets (conditional preference networks) is a simple and intuitive graphical tool for representing conditional preference statements over the values of a set of variables.( 软件学报 ISSN 1000-9825, CODEN RUXUEW Journal of Software,2012,23(6):1531−1541 [doi: 10.3724/SP.J.1001.2012.04090])

  7. Allocating tasks and resources • 處理家務： “Alice用吸塵器打掃和倒垃圾，Bob洗碗”VS“Alice倒垃圾，和Bob用吸塵器打掃和洗碗” 。 • 汽車使用分配權： “Alice只能在週五使用汽車，而Bob只能在週六和週日使用”VS“Bob週五和週六使用汽車上，和Alice在週日使用” 資源：特定一天汽車的使用權。“Alice在週五使用汽車，Bob在星期六 Carol在星期天”VS“Alice在星期五使用汽車，Bob在星期六、日使用， Carol不使用”，此分配對Alice是沒有分別的

  8. Allocating tasks and resources • 在經濟學中，假設Agent，給了她自己的資源和任務，不關心如何將剩餘的資源和任務分配給其他代理人被稱為 “no-externalities assumption”。 • 上述合理的假設，可以讓我們跳脫一般性的投票模式，而做出能更符合任務和資源分配相關問題的決定。 • 此類型的問題可應用在電腦科學上，我們可能會在某個時間分配的一台超級電腦（或其他計算資源），而不是一輛汽車。此外，不是分配一個家庭的家務，可能會用於分配工作的機器。

  9. Allocating tasks and resources • Pareto Efficiency • 帕累托最優(Pareto Efficiency)是指資源分發的一種理想狀態，即假定固有的一群人和可分發的資源，從一種分發狀態到另一種狀態的變化中，在沒有使任何人境況變壞的前提下，也不可能再使某些人的處境變好。 • 例如：某一個人擁有兩個左鞋，另一個人擁有兩個右鞋。

  10. Kidney exchanges • 一些患者的家人願意捐出腎臟，但卻與親人所需器官不匹配，因此他們可以和另外一組病人及其家人結對互換器官 Donor A Patient A Donor B Patient B Donor C Patient C

  11. Setting with Payments • Auctions and Exchanges • Combinatorial Auctions • Charitable Giving • Prediction Market

  12. Auctions and Exchanges • English auction • Candle auction • Dutch auction • Sealed-bid auction • Reverse auction • Multiple resources or tasks • Substitutes • Complements • Examples: ebay, Yahoo!

  13. Combinatorial Auctions • Substitutability and complementarity make it suboptimal to sell the resources in separate auctions. • We can let the bidder expresses a value for every non-empty subset(bundle) of the items. For example : pay $10 for item A, pay $7 for item A and B. (Using OR, XOR , XOR-of-OR, OR-of-XOR, OR/XOR…etc language) • Combinatorial auctions are more than a theoretical curiosity: they are used in practice in settings where the items display significant complementarities.(radio spectrum, reverse auction for strategic sourcing) Source from:香港電訊管理局 2010-11年營運基金報告書

  14. Combinatorial Auctions • Example :Google AdWords

  15. Charitable Giving • What do you think about the donations ? • Why should I make a donation？ • How do they use my money？ • What are the results？ • The author proposed a system to collect donations for the victims of the Indian Ocean tsunami and the victims of the Hurricane Katrina. • About 75% of the donors made their donations conditional on the total amount collected, suggesting that donors appreciated being able to do so. • The tsunami event was conducted among the participants of workshop while the hurricane event was open to everyone. • More recent systems also allow donors to make their donations conditional only on donations from selected parties, taking social network structure into account.

  16. Charitable Giving • Example : Yahoo!公益

  17. Prediction Market • A prediction market concerns a particular future event whose outcome is currently uncertain. • The agents trading in the prediction market cannot significantly influence the outcome of the event. • Examples : 運動彩券、未來事件交易所

  18. Strategic Behavior : Game Theory and Mechanism Design • Are the agents incentivized to communicate their preferences and beliefs truthfully, or can they benefit from misreporting them? • Game theory is a study of strategic decision making.An alternative term suggested "as a more descriptive name for the discipline" is interactive decision theory. (from Wikipedia) • Example1-分家產: • 一戶人家兩兄弟因分家產問題而鬧上官府，知縣大人決定- 先讓老大來將家產分為兩份，接著再讓老二優先選擇要哪一份 • Example2: • 2-player, 2-strategy game

  19. Strategic Behavior : Game Theory and Mechanism Design • Unfortunately , it turns out that in general voting settings, no good truthful mechanisms exist, by a result known as the Gibbard-Satterthwaite impossibility theorem. • For settings such as auctions and exchanges, there are more positive results, ex: second-price sealed-bid auction. • We can use computers not only to run existing mechanisms from scratch. This approach is automated mechanism design. • Another import issue is that the mechanisms from traditional mechanism design mainly guard against a single type of manipulation: misreporting one’s preferences. • The final direction in mechanism design concerns extending its techniques to dynamic environments.

  20. Conclusion • Increased computing power and better algorithms enable the use of mechanisms that were considered impractical. • Internet provide a great platform for spatially distributed users to communicate their preferences. • More Web-Based mechanism will be oriented around social networking sites such as Facebook and MySpace. • The computer scientist and economists are now seen working closer and closer.

  21. The End Thank you! Any questions ?

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