Dagstuhl Seminar Proceedings, Volume 7271

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07271 Abstracts Collection – Computational Social Systems and the Internet

Authors: Peter Cramton, Rudolf Müller, Eva Tardos, and Moshe Tennenholtz

Abstract

From 01.07. to 06.07.2007, the Dagstuhl Seminar 07271 ``Computational Social Systems and the Internet'' was held in the International Conference and Research Center (IBFI), Schloss Dagstuhl. During the seminar, several participants presented their current research, and ongoing work and open problems were discussed. Abstracts of the presentations given during the seminar as well as abstracts of seminar results and ideas are put together in this paper. The first section describes the seminar topics and goals in general. Links to extended abstracts or full papers are provided, if available.

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Peter Cramton, Rudolf Müller, Eva Tardos, and Moshe Tennenholtz. 07271 Abstracts Collection – Computational Social Systems and the Internet. In Computational Social Systems and the Internet. Dagstuhl Seminar Proceedings, Volume 7271, pp. 1-25, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2007)

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@InProceedings{cramton_et_al:DagSemProc.07271.1,
  author =	{Cramton, Peter and M\"{u}ller, Rudolf and Tardos, Eva and Tennenholtz, Moshe},
  title =	{{07271 Abstracts Collection – Computational Social Systems and the Internet }},
  booktitle =	{Computational Social Systems and the Internet},
  pages =	{1--25},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2007},
  volume =	{7271},
  editor =	{Peter Cramton and Rudolf M\"{u}ller and Eva Tardos and Moshe Tennenholtz},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagSemProc.07271.1},
  URN =		{urn:nbn:de:0030-drops-11666},
  doi =		{10.4230/DagSemProc.07271.1},
  annote =	{Keywords: Mechanism Design, Combinatorial Auctions, Social Choice Theory, Behavioral Economics, Computational Game Theory, Social Networks}
}

Document

DOI: 10.4230/DagSemProc.07271.2

07271 Summary – Computational Social Systems and the Internet

Authors: Peter Cramton, Rudolf Müller, Eva Tardos, and Moshe Tennenholtz

Abstract

The seminar "Computational Social Systems and the Internet" facilitated a very fruitful interaction between economists and computer scientists, which intensified the understanding of the other disciplines' tool sets. The seminar helped to pave the way to a unified theory of social systems on the Internet that takes into account both the economic and the computational issues---and their deep interaction.

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Peter Cramton, Rudolf Müller, Eva Tardos, and Moshe Tennenholtz. 07271 Summary – Computational Social Systems and the Internet. In Computational Social Systems and the Internet. Dagstuhl Seminar Proceedings, Volume 7271, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2007)

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@InProceedings{cramton_et_al:DagSemProc.07271.2,
  author =	{Cramton, Peter and M\"{u}ller, Rudolf and Tardos, Eva and Tennenholtz, Moshe},
  title =	{{07271 Summary – Computational Social Systems and the Internet }},
  booktitle =	{Computational Social Systems and the Internet},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2007},
  volume =	{7271},
  editor =	{Peter Cramton and Rudolf M\"{u}ller and Eva Tardos and Moshe Tennenholtz},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagSemProc.07271.2},
  URN =		{urn:nbn:de:0030-drops-11642},
  doi =		{10.4230/DagSemProc.07271.2},
  annote =	{Keywords: Mechanism Design, Combinatorial Auctions, Social Choice Theory, Behavioral Economics, Computational Game Theory, Social Networks}
}

Document

DOI: 10.4230/DagSemProc.07271.3

An Axiomatic Approach to Personalized Ranking Systems

Authors: Alon Altman and Moshe Tennenholtz

Abstract

Personalized ranking systems and trust systems are an essential tool for collaboration in a multi-agent environment. In these systems, trust relations between many agents are aggregated to produce a personalized trust rating of the agents. In this paper we introduce the first extensive axiomatic study of this setting, and explore a wide array of well-known and new personalized ranking systems. We adapt several axioms (basic criteria) from the literature on global ranking systems to the context of personalized ranking systems, and fully classify the set of systems that satisfy all of these axioms. We further show that all these axioms are necessary for this result.

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Alon Altman and Moshe Tennenholtz. An Axiomatic Approach to Personalized Ranking Systems. In Computational Social Systems and the Internet. Dagstuhl Seminar Proceedings, Volume 7271, pp. 1-25, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2007)

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@InProceedings{altman_et_al:DagSemProc.07271.3,
  author =	{Altman, Alon and Tennenholtz, Moshe},
  title =	{{An Axiomatic Approach to Personalized Ranking Systems}},
  booktitle =	{Computational Social Systems and the Internet},
  pages =	{1--25},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2007},
  volume =	{7271},
  editor =	{Peter Cramton and Rudolf M\"{u}ller and Eva Tardos and Moshe Tennenholtz},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagSemProc.07271.3},
  URN =		{urn:nbn:de:0030-drops-11527},
  doi =		{10.4230/DagSemProc.07271.3},
  annote =	{Keywords: Ranking systems, trust, axiomatization, incentives, mechanism design, game theory}
}

Document

DOI: 10.4230/DagSemProc.07271.4

Anonymity-Proof Voting Rules

Authors: Vincent Conitzer

Abstract

A (randomized, anonymous) voting rule maps any multiset of total orders of (aka. votes over) a fixed set of alternatives to a probability distribution over these alternatives. A voting rule f is neutral if it treats all alternatives symmetrically. It satisfies participation if no voter ever benefits from not casting her vote. It is falsename-proof if no voter ever benefits from casting additional (potentially different) votes. It is anonymity-proof if it satisfies participation and it is false-name-proof. We show that the class of anonymity-proof neutral voting rules consists exactly of the rules of the following form. With some probability kf in [0, 1], the rule chooses an alternative at random. With probability 1-kf , the rule first draws a pair of alternatives at random. If every vote prefers the same alternative between the two (and there is at least one vote), then the rule chooses that alternative. Otherwise, the rule flips a fair coin to decide between the two alternatives.

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Vincent Conitzer. Anonymity-Proof Voting Rules. In Computational Social Systems and the Internet. Dagstuhl Seminar Proceedings, Volume 7271, pp. 1-15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2007)

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@InProceedings{conitzer:DagSemProc.07271.4,
  author =	{Conitzer, Vincent},
  title =	{{Anonymity-Proof Voting Rules}},
  booktitle =	{Computational Social Systems and the Internet},
  pages =	{1--15},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2007},
  volume =	{7271},
  editor =	{Peter Cramton and Rudolf M\"{u}ller and Eva Tardos and Moshe Tennenholtz},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagSemProc.07271.4},
  URN =		{urn:nbn:de:0030-drops-11658},
  doi =		{10.4230/DagSemProc.07271.4},
  annote =	{Keywords: Mechanism design, social choice, false-name-proofness, verifying identities, combinatorial auctions}
}

Document

DOI: 10.4230/DagSemProc.07271.5

Auction Design with Avoidable Fixed Costs: An Experimental Approach

Authors: Wedad Elmaghraby and Nathan Larson

Abstract

Advances in information technology and computational power have opened the doors for auctioneers to explore a range of auction formats by considering varying degrees of bid expressivity and different payment rule, e.g., single price vs. discriminatory prices. While it is clear that one can design more complicated auctions, it is still not clear if should do so and which auction parameters have the greatest impact on the performance on cost and efficiency. The purpose of this paper is to gain some insight into this question, via analytical and experimental methods.

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Wedad Elmaghraby and Nathan Larson. Auction Design with Avoidable Fixed Costs: An Experimental Approach. In Computational Social Systems and the Internet. Dagstuhl Seminar Proceedings, Volume 7271, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2007)

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@InProceedings{elmaghraby_et_al:DagSemProc.07271.5,
  author =	{Elmaghraby, Wedad and Larson, Nathan},
  title =	{{Auction Design with Avoidable Fixed Costs: An Experimental Approach}},
  booktitle =	{Computational Social Systems and the Internet},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2007},
  volume =	{7271},
  editor =	{Peter Cramton and Rudolf M\"{u}ller and Eva Tardos and Moshe Tennenholtz},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagSemProc.07271.5},
  URN =		{urn:nbn:de:0030-drops-11579},
  doi =		{10.4230/DagSemProc.07271.5},
  annote =	{Keywords: Auctions, Experimental, Procurement, Synergies, Asymmetric Bidders}
}

Document

DOI: 10.4230/DagSemProc.07271.6

Incentive Compatible Regression Learning

Authors: Ofer Dekel, Felix Fischer, and Ariel D. Procaccia

Abstract

We initiate the study of incentives in a general machine learning framework. We focus on a game theoretic regression learning setting where private information is elicited from multiple agents, which are interested in different distributions over the sample space. This conflict potentially gives rise to untruthfulness on the part of the agents. In the restricted but important case when distributions are degenerate, and under mild assumptions, we show that agents are motivated to tell the truth. In a more general setting, we study the power and limitations of mechanisms without payments. We finally establish that, in the general setting, the VCG mechanism goes a long way in guaranteeing truthfulness and efficiency.

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Ofer Dekel, Felix Fischer, and Ariel D. Procaccia. Incentive Compatible Regression Learning. In Computational Social Systems and the Internet. Dagstuhl Seminar Proceedings, Volume 7271, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2007)

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@InProceedings{dekel_et_al:DagSemProc.07271.6,
  author =	{Dekel, Ofer and Fischer, Felix and Procaccia, Ariel D.},
  title =	{{Incentive Compatible Regression Learning}},
  booktitle =	{Computational Social Systems and the Internet},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2007},
  volume =	{7271},
  editor =	{Peter Cramton and Rudolf M\"{u}ller and Eva Tardos and Moshe Tennenholtz},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagSemProc.07271.6},
  URN =		{urn:nbn:de:0030-drops-11622},
  doi =		{10.4230/DagSemProc.07271.6},
  annote =	{Keywords: Machine learning, regression, mechanism design}
}

Document

DOI: 10.4230/DagSemProc.07271.7

Inefficiency of equilibria in query auctions with continuous valuations

Authors: Elena Grigorieva, P. Jean-Jacques Herings, Rudolf Müller, and Dries Vermeulen

Abstract

We show that, when bidders have continuous valuations, any ex post equilibrium in an ex post individually rational query auction can only be ex post efficient when the running time of the auction is infinite for almost all realizations of valuations of the bidders. In contrast we show that, when we allow for inefficient allocations with arbitrarily small probability, there is a query auction (to be more specific, a bisection auction) that attains this level of approximate efficiency in equilibrium, while additionally the running time of the auction in equilibrium is finite for all realizations of valuations.

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Elena Grigorieva, P. Jean-Jacques Herings, Rudolf Müller, and Dries Vermeulen. Inefficiency of equilibria in query auctions with continuous valuations. In Computational Social Systems and the Internet. Dagstuhl Seminar Proceedings, Volume 7271, pp. 1-9, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2007)

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@InProceedings{grigorieva_et_al:DagSemProc.07271.7,
  author =	{Grigorieva, Elena and Herings, P. Jean-Jacques and M\"{u}ller, Rudolf and Vermeulen, Dries},
  title =	{{Inefficiency of equilibria in query auctions with continuous valuations}},
  booktitle =	{Computational Social Systems and the Internet},
  pages =	{1--9},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2007},
  volume =	{7271},
  editor =	{Peter Cramton and Rudolf M\"{u}ller and Eva Tardos and Moshe Tennenholtz},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagSemProc.07271.7},
  URN =		{urn:nbn:de:0030-drops-11616},
  doi =		{10.4230/DagSemProc.07271.7},
  annote =	{Keywords: Query auctions, ex post equilibrium, efficiency}
}

Document

DOI: 10.4230/DagSemProc.07271.8

Item Pricing for Revenue Maximization in Combinatorial Auctions

Authors: Maria-Florina Balcan

Abstract

Consider the problem of a retailer with various goods for sale, attempting to set prices to maximize revenue. If customers have separate valuations over the different goods, and these are known to the retailer, then the goods can be priced separately and the problem is not so difficult. However, when customers have valuations over sets of items, this becomes a combinatorial auction problem, and the problem becomes computationally hard even when valuations are fully known in advance. In this talk we present some simple randomized algorithms and mechanisms for a number of interesting cases of this problem, both in the limited and unlimited supply setting. This talk is based on joint work with Avrim Blum and Yishay Mansour.

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Maria-Florina Balcan. Item Pricing for Revenue Maximization in Combinatorial Auctions. In Computational Social Systems and the Internet. Dagstuhl Seminar Proceedings, Volume 7271, pp. 1-2, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2007)

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@InProceedings{balcan:DagSemProc.07271.8,
  author =	{Balcan, Maria-Florina},
  title =	{{Item Pricing for Revenue Maximization in Combinatorial Auctions}},
  booktitle =	{Computational Social Systems and the Internet},
  pages =	{1--2},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2007},
  volume =	{7271},
  editor =	{Peter Cramton and Rudolf M\"{u}ller and Eva Tardos and Moshe Tennenholtz},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagSemProc.07271.8},
  URN =		{urn:nbn:de:0030-drops-11534},
  doi =		{10.4230/DagSemProc.07271.8},
  annote =	{Keywords: Item Pricing, Revenue Maximizing, Combinatorial Auctions}
}

Document

DOI: 10.4230/DagSemProc.07271.9

License Auctions with Royalty Contracts for (Winners and) Losers

Authors: Elmar Wolfstetter and Thomas Giebe

Abstract

This paper revisits the licensing of a non--drastic process innovation by an outside innovator to a Cournot oligopoly. We propose a new mechanism that combines a restrictive license auction with royalty licensing. This mechanism is more profitable than standard license auctions, auctioning royalty contracts, fixed--fee licensing, pure royalty licensing, and two-part tariffs. The key features are that royalty contracts are auctioned and that losers of the auction are granted the option to sign a royalty contract. Remarkably, combining royalties for winners and losers makes the integer constraint concerning the number of licenses irrelevant.

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Elmar Wolfstetter and Thomas Giebe. License Auctions with Royalty Contracts for (Winners and) Losers. In Computational Social Systems and the Internet. Dagstuhl Seminar Proceedings, Volume 7271, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2007)

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@InProceedings{wolfstetter_et_al:DagSemProc.07271.9,
  author =	{Wolfstetter, Elmar and Giebe, Thomas},
  title =	{{License Auctions with Royalty Contracts for (Winners and) Losers}},
  booktitle =	{Computational Social Systems and the Internet},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2007},
  volume =	{7271},
  editor =	{Peter Cramton and Rudolf M\"{u}ller and Eva Tardos and Moshe Tennenholtz},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagSemProc.07271.9},
  URN =		{urn:nbn:de:0030-drops-11514},
  doi =		{10.4230/DagSemProc.07271.9},
  annote =	{Keywords: Auctions, Patents, Licensing}
}

Document

DOI: 10.4230/DagSemProc.07271.10

Limited Verification of Identities to Induce False-Name-Proofness

Authors: Vincent Conitzer

Abstract

In open, anonymous environments such as the Internet, mechanism design is complicated by the fact that a single agent can participate in the mechanism under multiple identifiers. One way to address this is to design false-name-proof mechanisms, which choose the outcome in such a way that agents have no incentive to use more than one identifier. Unfortunately, there are inherent limitations on what can be achieved with false-name-proof mechanisms, and at least in some cases, these limitations are crippling. An alternative approach is to verify the identities of all agents. This imposes significant overhead and removes any benefits from anonymity. In this paper, we propose a middle ground. Based on the reported preferences, we check, for various subsets of the reports, whether the reports in the subset were all submitted by different agents. If they were not, then we discard some of them. We characterize when such a limited verification protocol induces false-name-proofness for a mechanism, that is, when the combination of the mechanism and the verification protocol gives the agents no incentive to use multiple identi- fiers. This characterization leads to various optimization problems for minimizing verification effort. We study how to solve these problems. Throughout, we use combinatorial auctions (using the Clarke mechanism) and majority voting as examples.

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Vincent Conitzer. Limited Verification of Identities to Induce False-Name-Proofness. In Computational Social Systems and the Internet. Dagstuhl Seminar Proceedings, Volume 7271, pp. 1-10, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2007)

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@InProceedings{conitzer:DagSemProc.07271.10,
  author =	{Conitzer, Vincent},
  title =	{{Limited Verification of Identities to Induce False-Name-Proofness}},
  booktitle =	{Computational Social Systems and the Internet},
  pages =	{1--10},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2007},
  volume =	{7271},
  editor =	{Peter Cramton and Rudolf M\"{u}ller and Eva Tardos and Moshe Tennenholtz},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagSemProc.07271.10},
  URN =		{urn:nbn:de:0030-drops-11569},
  doi =		{10.4230/DagSemProc.07271.10},
  annote =	{Keywords: Mechanism design, social choice, false-name-proofness, verifying identities, combinatorial auctions}
}

Document

DOI: 10.4230/DagSemProc.07271.11

On Revenue Equivalence in Truthful Mechanisms

Authors: Birgit Heydenreich, Rudolf Müller, Marc Uetz, and Rakesh Vohra

Abstract

The property of an allocation rule to be implementable in dominant strategies by a unique payment scheme is called revenue equivalence. In this paper we give a characterization of revenue equivalence based on a graph theoretic interpretation of the incentive compatibility constraints. The characterization holds for any (possibly infinite) outcome space and many of the known results about revenue equivalence are immediate consequences.

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Birgit Heydenreich, Rudolf Müller, Marc Uetz, and Rakesh Vohra. On Revenue Equivalence in Truthful Mechanisms. In Computational Social Systems and the Internet. Dagstuhl Seminar Proceedings, Volume 7271, pp. 1-4, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2007)

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@InProceedings{heydenreich_et_al:DagSemProc.07271.11,
  author =	{Heydenreich, Birgit and M\"{u}ller, Rudolf and Uetz, Marc and Vohra, Rakesh},
  title =	{{On Revenue Equivalence in Truthful Mechanisms}},
  booktitle =	{Computational Social Systems and the Internet},
  pages =	{1--4},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2007},
  volume =	{7271},
  editor =	{Peter Cramton and Rudolf M\"{u}ller and Eva Tardos and Moshe Tennenholtz},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagSemProc.07271.11},
  URN =		{urn:nbn:de:0030-drops-11581},
  doi =		{10.4230/DagSemProc.07271.11},
  annote =	{Keywords: Mechanism Design, Revenue Equivalence, Graph Theory}
}

Document

DOI: 10.4230/DagSemProc.07271.12

Reducing Costly Information Acquisition in Auctions

Authors: Kate Larson

Abstract

Most auction research assumes that potential bidders have private information about their willingness to pay for an item. In reality, bidders often have to go through a costly information-gathering process in order to learn their valuations. Recent attempts at modelling this phenomena has brought to light complex strategic behavior arising from information-gathering, and has shown that traditional approaches to auction and mechanism design are not able to overcome it.

Cite as

Kate Larson. Reducing Costly Information Acquisition in Auctions. In Computational Social Systems and the Internet. Dagstuhl Seminar Proceedings, Volume 7271, pp. 1-7, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2007)

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@InProceedings{larson:DagSemProc.07271.12,
  author =	{Larson, Kate},
  title =	{{Reducing Costly Information Acquisition in Auctions}},
  booktitle =	{Computational Social Systems and the Internet},
  pages =	{1--7},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2007},
  volume =	{7271},
  editor =	{Peter Cramton and Rudolf M\"{u}ller and Eva Tardos and Moshe Tennenholtz},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagSemProc.07271.12},
  URN =		{urn:nbn:de:0030-drops-11592},
  doi =		{10.4230/DagSemProc.07271.12},
  annote =	{Keywords: Auctions, Information Gathering}
}

Document

DOI: 10.4230/DagSemProc.07271.13

Signalling Preferences in Interviewing Markets

Authors: Robin S. Lee and Michael A. Schwarz

Abstract

The process of match formation in matching markets can be divided into three parts: information sharing, investments in information acquisition, and the formation of matches based on available information. The last stage where agents are assumed to know their preferences has been studied in seminal work of Gale and Shapley (1962), and a model of second stage costly information acquisition is introduced and studied in Lee and Schwarz (2007). This paper focuses on the first stage – information sharing – and examines mechanisms which allow workers to signal their preferences over matching partners prior to the assignment of interviews. The incentives of firms and workers vis-a-vis information revelation are partially aligned – all other things being equal, a worker prefers to have an interview with a firm that is high in his preference ranking and a firm prefers to invest in interviewing a worker who ranks a firm highly because such worker is more likely to accept a job if offered. However, the incentives are far from being perfectly aligned. For instance, if firms pay the full cost of interviewing, each worker would prefer to have as many interviews as possible, and in a world with bilateral communication no information is revealed as each workers would want to tell each firm that it is his first choice. But if communication is moderated through an intermediary or there is a restriction on the number of messages a worker can send, then cheap talk becomes informative. Currently existing market institutions that facilitate information exchange prior to interviewing are discussed.

Cite as

Robin S. Lee and Michael A. Schwarz. Signalling Preferences in Interviewing Markets. In Computational Social Systems and the Internet. Dagstuhl Seminar Proceedings, Volume 7271, pp. 1-12, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2007)

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@InProceedings{lee_et_al:DagSemProc.07271.13,
  author =	{Lee, Robin S. and Schwarz, Michael A.},
  title =	{{Signalling Preferences in Interviewing Markets}},
  booktitle =	{Computational Social Systems and the Internet},
  pages =	{1--12},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2007},
  volume =	{7271},
  editor =	{Peter Cramton and Rudolf M\"{u}ller and Eva Tardos and Moshe Tennenholtz},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagSemProc.07271.13},
  URN =		{urn:nbn:de:0030-drops-11635},
  doi =		{10.4230/DagSemProc.07271.13},
  annote =	{Keywords: Cheap talk, job search, labor market, matching,}
}

Document

DOI: 10.4230/DagSemProc.07271.14

Social Comparisons and Contributions to Online Communities: A Field Experiment on MovieLens

Authors: Yan Chen, Maxwell Harper, Joseph Konstan, and Sherry Li

Abstract

We explore the use of social comparison theory as a natural mechanism to increase contributions to an online movie recommendation community by investigating the effects of social information on user behavior in an online field experiment. We find that, after receiving behavioral information about the median user's total number of movie ratings, users below the median demonstrate a 530% increase in the number of monthly movie ratings, while those above the median decrease their monthly ratings by 62%. Movements from both ends converge towards the median, indicating conformity towards a newly-established social norm in a community where such a norm had been absent. Furthermore, the social information has a more dramatic effect on those below the median, suggesting an interaction between conformity and competitive preferences. When given outcome information about the average user's net benefit score from the system, consistent with social preference theory, users with net benefit scores above average contribute 94% of the new updates in the database. In both treatments, we find a highly significant Red Queen Effect.

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Yan Chen, Maxwell Harper, Joseph Konstan, and Sherry Li. Social Comparisons and Contributions to Online Communities: A Field Experiment on MovieLens. In Computational Social Systems and the Internet. Dagstuhl Seminar Proceedings, Volume 7271, pp. 1-7, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2007)

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@InProceedings{chen_et_al:DagSemProc.07271.14,
  author =	{Chen, Yan and Harper, Maxwell and Konstan, Joseph and Li, Sherry},
  title =	{{Social Comparisons and Contributions to Online Communities: A Field Experiment on MovieLens}},
  booktitle =	{Computational Social Systems and the Internet},
  pages =	{1--7},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2007},
  volume =	{7271},
  editor =	{Peter Cramton and Rudolf M\"{u}ller and Eva Tardos and Moshe Tennenholtz},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagSemProc.07271.14},
  URN =		{urn:nbn:de:0030-drops-11550},
  doi =		{10.4230/DagSemProc.07271.14},
  annote =	{Keywords: Social comparison, conformity, public goods, embedded online field experiment}
}

Document

DOI: 10.4230/DagSemProc.07271.15

Strategic Behavior in Multi-unit Assignment Problems: Theory and Evidence from Course Allocations

Authors: Eric Budish and Estelle Cantillon

Abstract

This paper analyses the assignment problem when agents have multi-unit demand. Applications include task assignment in a team, course allocation, sport drafts and any other allocation problem where money does not play a role in balancing supply and demand. There is no known allocation mechanism that is ex-post efficient, strategyproof and minimally fair, and practical solutions must therefore trade off these different aspects. We study such a specific mechanism used at Harvard Business School to allocate courses to students. We argue that students in the HBS mechanism have an incentive to overreport their preferences for popular courses, that this incentive does not vanish with the size of the market and that it results in increased congestion. We confirm these predictions with detailed data on reported preferences and behavior in the HBS mechanism. We show that strategic behavior hurts students but that it might still be preferable to random serial dictatorship over course bundles, a strategyproof alternative.

Cite as

Eric Budish and Estelle Cantillon. Strategic Behavior in Multi-unit Assignment Problems: Theory and Evidence from Course Allocations. In Computational Social Systems and the Internet. Dagstuhl Seminar Proceedings, Volume 7271, p. 1, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2007)

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@InProceedings{budish_et_al:DagSemProc.07271.15,
  author =	{Budish, Eric and Cantillon, Estelle},
  title =	{{Strategic Behavior in Multi-unit Assignment Problems: Theory and Evidence from Course Allocations}},
  booktitle =	{Computational Social Systems and the Internet},
  pages =	{1--1},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2007},
  volume =	{7271},
  editor =	{Peter Cramton and Rudolf M\"{u}ller and Eva Tardos and Moshe Tennenholtz},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagSemProc.07271.15},
  URN =		{urn:nbn:de:0030-drops-11544},
  doi =		{10.4230/DagSemProc.07271.15},
  annote =	{Keywords: Course allocation, market design, assignment, multi-unit demand}
}

Document

DOI: 10.4230/DagSemProc.07271.16

Strategy-proof assignment with a vanishing budget surplus

Authors: Hervé Moulin

Abstract

A VCG mechanism to assign p identical objects is feasible is cash transfers yield no deficit. The efficiency loss of such a mechanism is the worst ratio of budget surplus to efficient surplus. We compute the optimal efficiency loss for all n and p, when we also require Voluntary Participation as well as when we do not. Without the VP requirement, the optimal efficiency loss converges to zero uniformly in p, and exponentially fast if p is fixed. With the VP requirement asymptotic budget balance is only true is p is not larger than n/2.

Cite as

Hervé Moulin. Strategy-proof assignment with a vanishing budget surplus. In Computational Social Systems and the Internet. Dagstuhl Seminar Proceedings, Volume 7271, pp. 1-12, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2007)

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@InProceedings{moulin:DagSemProc.07271.16,
  author =	{Moulin, Herv\'{e}},
  title =	{{Strategy-proof assignment with a vanishing budget surplus}},
  booktitle =	{Computational Social Systems and the Internet},
  pages =	{1--12},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2007},
  volume =	{7271},
  editor =	{Peter Cramton and Rudolf M\"{u}ller and Eva Tardos and Moshe Tennenholtz},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagSemProc.07271.16},
  URN =		{urn:nbn:de:0030-drops-11608},
  doi =		{10.4230/DagSemProc.07271.16},
  annote =	{Keywords: VCG mechanisms, assignment, asymptotic budget balance, worst case analysis}
}

Dagstuhl Seminar Proceedings, Volume 7271

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