
James Schummer
Research Page
Contact Information
James Schummer
MEDS, Kellogg School of Management
Northwestern University
Evanston, IL 60208–2009, USA

Phone: 8474915151
Fax: 8474671220
MEDS Dept.: 8474913603

Curriculum Vitae (pdf)
Current Work
 “Incentives in Landing Slot Problems” (with Azar Abizada).
 Download LandingSlots.pdf (version: October 2013).
 Abstract:
In assignment problems motivated by rescheduling flights to airport landing slots, we
consider airline incentives to report (i) feasible arrival times, (ii) delay costs, or (iii) cancelations.
We show that any such incentive constraint restricts us to partially efficient mechanisms (like the FAA’s).
We construct such mechanisms inducing truthful reports of (ii) and (iii)
(unlike the FAA’s mechanism; see Schummer and Vohra, 2013), and weakly doing so for (i).
Our approach reinterprets such assignment problems as 2sided matching problems.
While reminiscent of School Choice modeling (Abdulkadiroğlu and Sönmez, 2003),
our results differ since airlines consume multiple objects (slots) and this application implies different constraints.
 “Strategic Sincerity” (with Rodrigo Velez).
 This is work in progress.
 “Voting with Money” (with Rakesh V. Vohra).
 This is work in progress.
 A preliminary version is available upon request.
 “Surplus Sharing with several Projects” (with François Maniquet).
 This is work in progress.
Published Papers
 “Assignment of Arrival Slots” (with Rakesh V. Vohra).
 American Economic Journal: Microeconomics (2013) 5:2, 164–185.
 Download: slotsAEJM.pdf.
 View at AEAweb.
 Abstract:
During inclement weather, the FAA reassigns vacated airport landing slots within a certain time interval.
We consider this mechanism design problem when a preexisting landing schedule defines certain
property rights for the airlines.
This particular problem has been analyzed from an operational perspective,
where the motivation for the FAA’s current mechanism—the Compression Algorithm—rests
on incentives and property rights.
This paper appears to be the first to rigorously formalize these two notions for this application.
Our results show that the Compression Algorithm satisfies a certain form of incentive compatibility
but fails a certain interpretation of property rights.
We then provide an example of a mechanism that satisfies both conditions;
proofs of this use a different but related matching model.
Neither mechanism, however, would always gives airlines the incentive to vacate unusable landing slots if
airlines can prevent the slot’s inclusion in either of these trading algorithms.
 “An Ascending Vickrey Auction for Selling Bases of a Matroid”
(with Sushil Bikhchandani, Sven de Vries, and Rakesh V. Vohra).
 Operations Research (2011) 59:2, 400–413.
 Download: MatroidOR2011.pdf. Also see the eCompanion.
 View at Informs Online.
 Abstract:
Consider selling bundles of indivisible goods to buyers
with concave utilities that are additively separable in money and goods.
We propose an ascending auction for the case when the seller is
constrained to sell bundles whose elements form a basis of a
matroid. It extends easily to polymatroids.
Applications include scheduling (Demange, Gale, and Sotomayor, 1986),
allocation of homogeneous goods (Ausubel, 2004),
and spatially distributed markets (Babaioff, Nisan, and Pavlov, 2004).
Our ascending auction induces buyers to bid
truthfully, and returns the economically efficient basis.
Unlike other ascending auctions for this environment,
ours runs in pseudopolynomial or polynomial time.
Furthermore we prove the impossibility of
an ascending auction for nonmatroidal independence setsystems.
 “Credible Deviations from Signaling Equilibria” (with Péter Esö).
 International Journal of Game Theory (2009) 48:3, 411–430.
 View at SpringerLink.
 Download final version: CDC.pdf.
 Our final “working paper version”
contains more information plus extra discussion about refinements that does not appear
in the published version. For those interested in a deeper reading on this topic, within
the context of the refinements literature, I recommend reading this preeditorialized version.
In the past we have received positive comments about the helpfulness of this version’s extra discussion.
 The supplemental appendix proves some claims
and provides more examples.
 Abstract:
In SenderReceiver games with costly signaling, some equilibria are
vulnerable to deviations which could be “unambiguously” interpreted by
the Receiver as coming from a unique set of possible Sendertypes.
The vulnerability occurs when the types in this set are the ones who
gain from the deviation, regardless of the posterior beliefs the
Receiver forms over that set.
We formalize this idea and use it to characterize a unique equilibrium
outcome in two classes of games.
First, in monotonic signaling games, only the Riley outcome is immune
to this sort of deviation.
Our result therefore provides a plausible story behind the selection
made by Cho and Kreps’ (1987) D1 criterion on this class of games.
Second we examine a version of Crawford and Sobel’s (1982) model but
with costly signaling and finite type sets, where standard refinements have no effect.
We show that only a Rileylike separating equilibrium is immune to these deviations.

“Mechanism Design without Money” (with Rakesh V. Vohra).
 This is a chapter in the book
Algorithmic
Game Theory (Nisan, Roughgarden, Tardos, Vazirani, eds.), Cambridge University Press, 2007.
 Abstract:
Despite impossibility results on general domains, there are some classes of
situations in which there exist interesting dominantstrategy mechanisms. While
some of these situations (and the resulting mechanisms) involve the transfer of
money, we examine some that do not. Specifically, we analyze: problems where
agents have singlepeaked preferences over a 1dimensional public policy
space; problems where agents can trade/consume a single, indivisible private
good; and problems where agents must match with each other.
 “On Ascending Vickrey Auctions for Heterogeneous Objects” (with
Sven de Vries and Rakesh V. Vohra).
 Journal of Economic Theory (2007) 132:1, 95–118.
 View at ScienceDirect.
 Download the prepublication version.
 Abstract:
We construct an ascending auction for heterogeneous objects
by applying a primaldual algorithm to a linear program that
represents the efficientallocation problem for this setting.
The auction assigns personalized prices to bundles, and asks bidders
to report their preferred bundles in each round.
A bidder’s prices are increased when he belongs to a “minimally undersupplied” set
of bidders. We consider this concept to be the natural generalization
of an “overdemanded” set of objects, introduced by Demange et al. (1986)
for the onetoone assignment problem.
Under a submodularity condition, the auction implements the Vickrey–Clarke–Groves
outcome; we show that this type of condition is somewhat necessary to do so.
When classifying the ascendingauction literature in terms of their underlying algorithms,
our auction fills a gap in that literature.
We relate our results to the recent work of Ausubel and Milgrom (2002).
 Try out a
javascript applet
which executes the auction algorithm derived in the paper!
 “Almostdominant Strategy Implementation”
 Games and Economic Behavior (2004) 48, 154–170.
 View at ScienceDirect.
 Download the prepublication version.
 Abstract:
We examine the consequences of relaxing strategyproofness
(a form of dominant strategy implementation) by allowing
instances of “small” gains from manipulation.
In 2agent exchange economies, this relaxation is shown to have
a discontinuous effect on the range of efficient rules.
This demonstrates a type of nonrobustness in previous
impossibility results.
When small gains are measured with respect to a single good,
we show that a particular rule is, unambiguously,
most equitable among all efficient rules satisfying the relaxed condition.

“Bribing and Signaling in Secondprice Auctions” (with
Péter Esö)
 Games and Economic Behavior (2004) 47, 299–324.
 View at ScienceDirect.
 Download the prepublication version.
 The
Working
Paper version (Oct. 2002) contains related results.
 We have some unpublished
supplemental
notes on variations of the model in this paper.
 Abstract:
We examine whether a twobidder, secondprice auction for a single
good (with private, independent values) is immune to a simple form
of collusion, where one bidder may bribe the other to commit to
stay away from the auction (i.e. submit a bid of zero).
In either of two cases—where the potential bribe is fixed or
allowed to vary—the only robust equilibria involve bribing.
In the fixedbribe case, there is a unique such equilibrium.
In the variable bribes case, all robust equilibria involve low bribertypes
revealing themselves through the amount they offer, while all high
types offer the same bribe; only one such equilibrium is continuous.
Bribing in all cases causes inefficiency.

“Auctions for Procuring Options” (with Rakesh V. Vohra)
 Operations Research (2003) 51, 41–51.
 View at INFORMS.
 Abstract:
We examine the mechanism design problem for a single buyer to
procure purchaseoptions for a homogeneous good when that buyer is required
to satisfy an unknown future demand.
Suppliers have 2dimensional types in the form of commitment costs
and production costs.
The efficient schedule of options depends on the distribution of demand.
To implement an efficient outcome, we introduce a class of
mechanisms which are essentially pivotal mechanisms
(Vickrey–Clarke–Groves) with respect to the expected costs of
the suppliers.
We show that the computational task of running such mechanisms is
not burdensome.
Our discussion uses electricity markets as an example.

“Linear Programming and Vickrey Auctions” (with Sushil Bikhchandani,
Sven de Vries, and Rakesh V. Vohra)
 In
Mathematics
of the Internet: Eauction and Markets, an IMA Volume in
Mathematics and its Applications, Dietrich and Vohra, ed., Springer, 2002.
 Abstract:
The Vickrey sealed bid auction occupies a central place in auction theory
because of its efficiency and incentive properties.
Implementing the auction requires the auctioneer to solve n+1 optimization
problems, where n is the number of bidders.
In this paper we survey various environments (some old and some new)
where the payments bidders make under the Vickrey auction correspond to
dual variables in certain linear programs.
Thus, in these environments, at most two optimization
problems must be solved to determine the Vickrey outcome.
Furthermore, primaldual algorithms for some of these linear
programs suggest ascending auctions that implement the Vickrey outcome.

“Strategyproof Location on a Network” (with Rakesh V. Vohra)
 Journal of Economic Theory (2002) 104, 405–428.
 View at ScienceDirect.
 Download the prepublication version.
 Abstract:
We consider rules that choose a location on a graph (e.g. a
road network) based on agents’ singlepeaked preferences.
First, we characterize the class of strategyproof, onto rules
when the graph is a tree.
Such a rule is based on a collection of generalized
median voter rules (Moulin, 1980) satisfying a consistency condition.
Second, we characterize such rules for graphs containing cycles.
We show that while such a rule is not necessarily dictatorial,
the existence of a cycle grants some agent
an amount of decisive power, unlike the case of trees.
Rules for this case can be described
in terms of a subclass of such rules for trees.
Journal of Economic Literature Classification Numbers: C72, D78.
 “Constrained Egalitarianism: A New Solution for Claims Problems” (with Y. Chun and W. Thomson)
 Seoul Journal of Economics (2001) 14, 269–298.
 Contact me for a copy.
 Abstract:
We propose a new rule to solve claims problems (O’Neill 1982) and show that this rule
is best in achieving certain objectives of equality. We present three theorems describing
it as the most “egalitarian” among all rules satisfying two minor requirements,
“estatemonotonicity” and “the midpoint property.”
We refer to it as the “constrained egalitarian” rule.
We show that it is consistent and give a parametric representation of it.
We also define several other rules and relate all of them to the
rules that have been most commonly discussed in the literature.
Journal of Economic Literature Classification Numbers: D63, D70.
 “Manipulation through Bribes”
 Journal of Economic Theory (2000) 91, 180–198.
 This paper can be
downloaded.
 View at
ScienceDirect.
 Abstract:
We consider allocation rules that choose both an outcome
and transfers, based on the agents’ reported valuations of the outcomes.
Under a given allocation rule, a bribing situation exists when
agent j could pay agent i to misreport his valuations, resulting
in a net gain to both agents.
A rule is bribeproof if such opportunities never arise.
The central result is that when a bribeproof rule is used,
the resulting payoff to any one agent is a continuous
function of any other agent’s reported valuations.
We then show that on connected domains of valuation functions,
if either the set of outcomes is finite or
each agent’s set of admissible valuations is smoothly connected,
then an agent’s payoff is a constant function of other agents’
reported valuations.
Finally, under the additional assumption of a standard domainrichness
condition, we show that a bribeproof rule must be a constant function.
The results apply to a very broad class of economies.
 “Eliciting Preferences to Assign Positions and Compensation”
 Games and Economic Behavior (2000) 30, 293–318.
 View at
ScienceDirect.
 Abstract:
We describe strategyproof rules for economies where an agent is assigned a
position (e.g., a job) plus some of a divisible good. For the
2agent–2position case we derive a robust characterization. For the
multiagentposition case, many “arbitrary” such rules exist, so we consider
additional requirements. By also requiring coalitional strategyproofness or
nonbossiness, the range of a solution is restricted to the point that such
rules are not more complex than those for the ShapleyScarf housing model (no
divisible good). Third, we show that essentially only constant solutions are
immune to manipulations involving “bribes.” Finally, we demonstrate a
conflict between efficiency and strategyproofness. The results extend to
models (without externalities) in which agents share positions
 “Strategyproofness versus Efficiency for Small Domains of Preferences over Public Goods”
 Economic Theory (1999) 13, 709–722.
 See
this
paper at SpringerLink.
 Abstract:
It has long been known that when agents have von Neumann–Morgenstern
preferences over lotteries, there is an incompatibility between
strategyproofness and efficiency (Gibbard (1973), Hylland (1980))—a solution
satisfying those properties must be dictatorial. We strengthen this result
by showing that it follows from the same incompatibility on a series of much
smaller domains of preferences.
Specifically, we first show the incompatibility to hold on our
smallest domain, in which two agents are restricted to have linear
preferences over one private good and one public good produced from the
private good (Kolm triangle economies). This result then implies the same
incompatibility on increasingly larger domains of preferences, ending finally
with the class of von Neumann–Morgenstern preferences over lotteries.
 “Strategyproofness versus Efficiency on Restricted Domains of Exchange Economies”
 Social Choice and Welfare (1997) 14, 47–56.
 See
this
paper at SpringerLink.
 Abstract:
Strategyproofness has been shown to be a strong property, particularly on
large domains of preferences. We therefore examine the existence of
strategyproof and efficient solutions on restricted, 2person domains of
exchange economies. On the class of 2person exchange economies in which
agents have homothetic, strictly convex preferences we show, as Zhou (1991)
did for a larger domain, that such a solution is necessarily dictatorial. As
this proof requires preferences exhibiting high degrees of complementarity,
our search continues to a class of linear preferences. Even on this “small”
domain, the same negative result holds. These two results are extended to
many superdomains, including Zhou’s.
 “Two Derivations of the Uniform Rule and an Application to Bankruptcy”
(with William Thomson)
 Economics Letters (1997) 55, 333–337.
 View at
ScienceDirect.
 Abstract:
We consider the problem of allocating a single infinitely divisible commodity to agents with
singlepeaked preferences, and establish two properties of the rule that has played the
central role in the analysis of this problem, the uniform rule. Among the efficient allocations,
it selects (1) the one at which the difference between the largest amount received by any
agent and the smallest such amount is minimal, and (2) the one at which the variance of the
amounts received by all the agents is minimal. We also show that an important solution for
bankruptcy problems, the constrained equalaward solution, can be characterized by
analogous minimization exercises, subject to different constraints.
Unpublished Manuscripts
 “A Pedagogical Example of Nonconcavifiable Preferences”
(version: March 1998)
 Dissertation: “Strategyproof Allocation for Restricted Economic Domains”
(My Ph.D. dissertation, completed at the
University of Rochester in
1997, under the supervision of
William Thomson.)
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