263,417 research outputs found
Efficient minimal preference change
In this article, we study a minimal change approach to preference dynamics. We treat a set of preferences as a special kind of theory, and define minimal change preference contraction and revision operations in the spirit of the Alchourrón, Gärdenfors, and Makinson theory of belief revision. We characterise minimal contraction of preference sets by a set of postulates and prove a representation theorem. We also give a linear time algorithm which implements minimal contraction by a single preference. We then define minimal contraction by a set of preferences, and show that the problem of a minimal contraction by a set of preferences is NP-hard
Learning Dynamic Robot-to-Human Object Handover from Human Feedback
Object handover is a basic, but essential capability for robots interacting
with humans in many applications, e.g., caring for the elderly and assisting
workers in manufacturing workshops. It appears deceptively simple, as humans
perform object handover almost flawlessly. The success of humans, however,
belies the complexity of object handover as collaborative physical interaction
between two agents with limited communication. This paper presents a learning
algorithm for dynamic object handover, for example, when a robot hands over
water bottles to marathon runners passing by the water station. We formulate
the problem as contextual policy search, in which the robot learns object
handover by interacting with the human. A key challenge here is to learn the
latent reward of the handover task under noisy human feedback. Preliminary
experiments show that the robot learns to hand over a water bottle naturally
and that it adapts to the dynamics of human motion. One challenge for the
future is to combine the model-free learning algorithm with a model-based
planning approach and enable the robot to adapt over human preferences and
object characteristics, such as shape, weight, and surface texture.Comment: Appears in the Proceedings of the International Symposium on Robotics
Research (ISRR) 201
The distribution of oportunities: a normative theory
In this paper, we consider the problem of ranking protiles of opportunity sets. First, we take each agent's preferences over (individual) opportunity sets as given. Then, rather than discriminate
among possibly competing evaluative criteria, we consider minimal standards for any such ranking. We impose four normative principies, in each case limiting the conditions under which ethical conclusions might be drawn to only those cases that are unambiguous. The first three principles are subrestrictions of the Pareto criterion; they require that Pareto improvements unambiguously enhance social welfare only when they do not conflict with other social objectives. The fourth principle is a minimal equity condition. It requires that if an agent can be identified as being the worst-off, then a necessary condition for social welfare to unambiguously increase when sorne agents gain is that this agent gains as well, however slightly. We then study the properties of social optima under these restrictions. We show that while optima need not be Pareto efficient, they must be envy-free. Thus, accepting these principies requires commitment to a world in which no agent envies the opportunities available to another
Partial Strategyproofness: Relaxing Strategyproofness for the Random Assignment Problem
We present partial strategyproofness, a new, relaxed notion of
strategyproofness for studying the incentive properties of non-strategyproof
assignment mechanisms. Informally, a mechanism is partially strategyproof if it
makes truthful reporting a dominant strategy for those agents whose preference
intensities differ sufficiently between any two objects. We demonstrate that
partial strategyproofness is axiomatically motivated and yields a parametric
measure for "how strategyproof" an assignment mechanism is. We apply this new
concept to derive novel insights about the incentive properties of the
probabilistic serial mechanism and different variants of the Boston mechanism.Comment: Working Pape
Noise load management at Amsterdam Airport Schiphol
Amsterdam Airport Schiphol is one of the five primary hub-airports in Europe. All flight movements are controlled by Air Traffic Control the Netherlands (LVNL), whose main objective is to guarantee safety, efficiency, and protection of the environment, that includes noise load. To this end, a number of enforcement points is located in the vicinity of Schiphol. Each aircraft movement contributes to the noise load at these points. If the cumulative load in an aviation year at an enforcement point exceeds its maximum, the civil aviation authority may impose severe sanctions, such as fines, or a reduction in the number of aircraft movements. The latter is a typical restriction for Schiphol.\ud
Runway selection is carried out via the preference list, an ordered set of runway combinations such that the higher on the list a runway combination, the better this combination is for maintaining the noise load limit. The highest safe runway combination in the list will actually be used. This paper has formulated the preference list selection process in the mathematical framework of Stochastic Dynamic Programming that enables determining an optimal strategy for preference list selection taking into account future and unpredictable weather conditions, as well as safety and efficiency restrictions
Cell organization in soft media due to active mechanosensing
Adhering cells actively probe the mechanical properties of their environment
and use the resulting information to position and orient themselves. We show
that a large body of experimental observations can be consistently explained
from one unifying principle, namely that cells strengthen contacts and
cytoskeleton in the direction of large effective stiffness. Using linear
elasticity theory to model the extracellular environment, we calculate optimal
cell organization for several situations of interest and find excellent
agreement with experiments for fibroblasts, both on elastic substrates and in
collagen gels: cells orient in the direction of external tensile strain, they
orient parallel and normal to free and clamped surfaces, respectively, and they
interact elastically to form strings. Our method can be applied for rational
design of tissue equivalents. Moreover our results indicate that the concept of
contact guidance has to be reevaluated. We also suggest that cell-matrix
contacts are upregulated by large effective stiffness in the environment
because in this way, build-up of force is more efficient.Comment: Revtex, 7 pages, 4 Postscript files include
Repeated Rounds with Price Feedback in Experimental Auction Valuation: An Adversarial Collaboration
It is generally thought that market outcomes are improved with the provision of market information. As a result, the use of repeated rounds with price feedback has become standard practice in the applied experimental auction valuation literature. We conducted two experiments to determine how rationally subjects behave with and without price feedback in a second price auction. Results from an auction for lotteries show that subjects exposed to price feedback are significantly more likely to commit preference reversals. However, this irrationality diminishes in later rounds. Results from an induced value auction indicate that price feedback caused greater deviations from the Nash equilibrium bidding strategy. Our results suggest that while bidding on the same item repeatedly improves auction outcomes, this improvement is not the result of price feedback
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