73,366 research outputs found
Forming efficient agent groups for completing complex tasks
In this paper we produce complexity and impossibility results and develop algorithms for a task allocation problem that needs to be solved by a group of autonomous agents working together. In particular, each task is assumed to be composed of several subtasks and involves an associated predetermined and known overall payment (set by the task’s owner) for its completion. However, the division of this payment among the corresponding contributors is not predefined. Now to accomplish a particular task, all its subtasks need to be allocated to agents with the necessary capabilities and the agents’ corresponding costs need to fall within the preset overall task payment. For this scenario, we first provide a cooperative agent system designer with a practical solution that achieves an efficient allocation. However, this solution is not applicable for non-cooperative settings. Consequently, we go on to provide a detailed analysis where we prove that certain design goals cannot be achieved if the agents are self interested. Specifically, we prove that for the general case, no protocol achieving the efficient solution can exist that is individually rational and budget balanced. We show that although efficient protocols may exist in some settings, these will inevitably be setting-specific
Giant magnon bound states from strongly coupled N=4 SYM
We calculate in a very simple way the spectrum of giant magnon bound states
at strong coupling in N=4 SYM, by utilizing the description of the field theory
vacuum in terms of a condensate of eigenvalues of commuting matrices. We
further show that these calculations can be understood in terms of the central
charge extension that permits the calculation of BPS masses in the Coulomb
branch of N=4 SYM. This paper shows further evidence that the strong coupling
expansion of the maximally supersymmetric Yang-Mills theory in four dimensions
can be done systematically from first principles, without the assumption of
integrability.Comment: 19 pages, uses revte
High Grading Standards Improve Student Performance
Allgemeinbildende Schule, Schulpolitik, Qualifikation, Vereinigte Staaten, General schooling, School policy, Occupational qualification, United States
Interplay between strong correlations and magnetic field in the symmetric periodic Anderson model
Magnetic field effects in Kondo insulators are studied theoretically, using a
local moment approach to the periodic Anderson model within the framework of
dynamical mean-field theory. Our main focus is on field-induced changes in
single-particle dynamics and the associated hybridization gap in the density of
states. Particular emphasis is given to the strongly correlated regime, where
dynamics are found to exhibit universal scaling in terms of a field-dependent
low energy coherence scale. Although the bare applied field is globally
uniform, the effective fields experienced by the conduction electrons and the
-electrons differ because of correlation effects. A continuous
insulator-metal transition is found to occur on increasing the applied field,
closure of the hybridization gap reflecting competition between Zeeman
splitting and screening of the -electron local moments. For intermediate
interaction strengths the hybridization gap depends non-linearly on the applied
field, while in strong coupling its field dependence is found to be linear. For
the classic Kondo insulator YbB, good agreement is found upon direct
comparison of the field evolution of the experimental transport gap with the
theoretical hybridization gap in the density of states.Comment: 8 pages, 8 figure
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