32 research outputs found
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A Game-Theoretic Analysis of Games with a Purpose
We present a simple game-theoretic model for the ESP game, an interactive game devised to label images on the web, and characterize the equilibrium behavior of the model. We show that a simple change in the incentive structure can lead to different equilibrium structure and suggest the possibility of formal incentive design in achieving desirable system-wide outcomes, complementing existing considerations of robustness against cheating and human factors.Engineering and Applied Science
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A game-theoretic analysis of the ESP game
“Games with a Purpose” are interactive games that users play because they are fun, with the added benefit that the outcome of play is useful work. The ESP game, developed by [von Ahn and Dabbish 2004], is an example of such a game devised to label images on the web. Since labeling images is a hard problem for computer vision algorithms and can be tedious and time-consuming for humans, the ESP game provides humans with incentive to do useful work by being enjoyable to play. We present a simple game-theoretic model of the ESP game and characterize the equilibrium behavior in our model. Our equilibrium analysis supports the fact that users appear to coordinate on low effort words. We provide an alternate model of user preferences, modeling a change that could be induced through a different scoring method, and show that equilibrium behavior in this model coordinates on high effort words. We also give sufficient conditions for coordinating on high effort words to be a Bayesian-Nash equilibrium. Our results suggest the possibility of formal incentive design in achieving desirable system-wide outcomes for the purpose of human computation, complementing existing considerations of robustness against cheating and human factors.Engineering and Applied Science
Social Status and Badge Design
Many websites rely on user-generated content to provide value to consumers.
These websites typically incentivize participation by awarding users badges
based on their contributions. While these badges typically have no explicit
value, they act as symbols of social status within a community. In this paper,
we consider the design of badge mechanisms for the objective of maximizing the
total contributions made to a website. Users exert costly effort to make
contributions and, in return, are awarded with badges. A badge is only valued
to the extent that it signals social status and thus badge valuations are
determined endogenously by the number of users who earn each badge. The goal of
this paper is to study the design of optimal and approximately badge mechanisms
under these status valuations. We characterize badge mechanisms by whether they
use a coarse partitioning scheme, i.e. awarding the same badge to many users,
or use a fine partitioning scheme, i.e. awarding a unique badge to most users.
We find that the optimal mechanism uses both fine partitioning and coarse
partitioning. When status valuations exhibit a decreasing marginal value
property, we prove that coarse partitioning is a necessary feature of any
approximately optimal mechanism. Conversely, when status valuations exhibit an
increasing marginal value property, we prove that fine partitioning is
necessary for approximate optimality
Restricted Strip Covering and the Sensor Cover Problem
Given a set of objects with durations (jobs) that cover a base region, can we
schedule the jobs to maximize the duration the original region remains covered?
We call this problem the sensor cover problem. This problem arises in the
context of covering a region with sensors. For example, suppose you wish to
monitor activity along a fence by sensors placed at various fixed locations.
Each sensor has a range and limited battery life. The problem is to schedule
when to turn on the sensors so that the fence is fully monitored for as long as
possible. This one dimensional problem involves intervals on the real line.
Associating a duration to each yields a set of rectangles in space and time,
each specified by a pair of fixed horizontal endpoints and a height. The
objective is to assign a position to each rectangle to maximize the height at
which the spanning interval is fully covered. We call this one dimensional
problem restricted strip covering. If we replace the covering constraint by a
packing constraint, the problem is identical to dynamic storage allocation, a
scheduling problem that is a restricted case of the strip packing problem. We
show that the restricted strip covering problem is NP-hard and present an O(log
log n)-approximation algorithm. We present better approximations or exact
algorithms for some special cases. For the uniform-duration case of restricted
strip covering we give a polynomial-time, exact algorithm but prove that the
uniform-duration case for higher-dimensional regions is NP-hard. Finally, we
consider regions that are arbitrary sets, and we present an O(log
n)-approximation algorithm.Comment: 14 pages, 6 figure
Rating mechanisms for sustainability of crowdsourcing platforms
Crowdsourcing leverages the diverse skill sets of large collections of individual contributors to solve problems and execute projects, where contributors may vary significantly in experience, expertise, and interest in completing tasks. Hence, to ensure the satisfaction of its task requesters, most existing crowdsourcing platforms focus primarily on supervising contributors\u27 behavior. This lopsided approach to supervision negatively impacts contributor engagement and platform sustainability
Winner-Take-All Crowdsourcing Contests with Stochastic Production
We study winner-take-all contests for crowdsourcing procurement in a model of costly effort and stochastic production. The principal announces a prize value P, agents simultaneously select a level of costly effort to exert towards production, yielding stochastic quality results, and then the agent who produces the highest quality good is paid P by the principal. We derive conditions on the probabilistic mapping from effort to quality under which this contest paradigm yields efficient equilibrium outcomes, and demonstrate that the conditions are satisfied in a range of canonical settings