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931.
This study discusses the evolutionary nature of knowledge acquisition at micro and macro levels, and in particular when the process involves an artificial agent's interpretative devices. In order to accomplish this, we propose using an individual learning model (or inner‐world reconstruction model) that in our view overcomes neoclassic epistemological holdups and may increase the predictive power of computational economics, by letting an artificial agent's knowledge evolve by itself, irrespective of globally specified goals or individual motives of behavior; using simultaneous (or parallel) genetic algorithms (GA) to evolve a single agent's learning strategy, each GA with different general specifications, in a multiagent setting. © 2006 Wiley Periodicals, Inc. Complexity 11: 12–19, 2006 相似文献
932.
The two-dimensional Inelastic Maxwell Model (IMM) is studied by numerical simulations. It is shown how the inelasticity of collisions together with the fluctuations of the number of collisions undergone by a particle lead to energy fluctuations. These fluctuations are associated to a shrinking of the available phase space. We find the asymptotic scaling of these energy fluctuations and show how they affect the tail of the velocity distribution during long time intervals. We stress that these fluctuations relax like power laws on much slower time scales than the usual exponential relaxations taking place in kinetic theory. 相似文献
933.
N. G. Fytas A. Malakis 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,50(1-2):39-43
The three-dimensional bimodal random-field Ising model is studied
via a new finite temperature numerical approach. The methods of
Wang-Landau sampling and broad histogram are implemented in a
unified algorithm by using the N-fold version of the Wang-Landau
algorithm. The simulations are performed in dominant energy
subspaces, determined by the recently developed critical minimum
energy subspace technique. The random-fields are obtained from a
bimodal distribution, that is we consider the discrete
(±Δ) case and the model is studied on cubic lattices with
sizes 4≤L ≤20. In order to extract information for the
relevant probability distributions of the specific heat and
susceptibility peaks, large samples of random-field realizations
are generated. The general aspects of the model's scaling behavior
are discussed and the process of averaging finite-size anomalies
in random systems is re-examined under the prism of the lack of
self-averaging of the specific heat and susceptibility of the
model. 相似文献
934.
L. G. Molinari N. Manini 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,51(3):331-336
The many-body dynamics of interacting electrons in condensed matter and
quantum chemistry is often studied at the quasiparticle level, where the
perturbative diagrammatic series is partially resummed.
Based on Hedin's equations for self-energy, polarization, propagator,
effective potential, and vertex function,
dressed (skeleton) Feynman diagrams are enumerated.
Such diagram counts provide useful simple checks for extensions of the
theory for future realistic simulations. 相似文献
935.
F. Blanchini 《Journal of Optimization Theory and Applications》1990,65(1):29-40
The problem of control in the presence of unknown but limited disturbance for a discrete-time linear system with polyhedral input and state bounds is investigated. Two problems are considered: that of reaching an assigned target set in the state space; and that of keeping the state in a given region using the available controls. In both cases, a solution is given via linear programming. A computational procedure for the control synthesis is proposed which can be implemented to obtain a feedback control.The author thanks Professor G. Leitmann for his helpful suggestions. 相似文献
936.
We consider a finite-horizon control model with additive input. There are two convex functions which describe the running cost and the terminal cost within the system. The cost of input is proportional to the input and can take both positive and negative values. It is shown that there exists a deterministic control problem whose optimal cost is the same as the one in the stochastic control problem. The optimal policy for the stochastic problem consists of keeping the process as close to the optimal deterministic trajectory as possible.This research is supported by NSERC Grant A4619, MRCO, NSF Grant DMS-86-01510, and AFOSR Grant 87-0278. 相似文献
937.
We consider time discrete systems which are described by a system of difference equations. The related discrete optimal control problems are introduced. Additionally, a gametheoretic extension is derived, which leads to general multicriteria decision problems. The characterization of their optimal behavior is studied. Given starting and final states define the decision process; applying dynamic programming techniques suitable optimal solutions can be gained. We generalize that approach to a special gametheoretic decision procedure on networks. We characterize Nash equilibria and present sufficient conditions for their existence. A constructive algorithm is derived. The sufficient conditions are exploited to get the algorithmic solution. Its complexity analysis is presented and at the end we conclude with an extension to the complementary case of Pareto optima.Dmitrii Lozovanu was Supported by BGP CRDF-MRDA MOM2-3049-CS-03. 相似文献
938.
M. Palese 《Theoretical and Mathematical Physics》2005,144(1):1014-1021
We solve the Backlund problem for both the compact and noncompact versions of the Ishimori (2+1)-dimensional nonlinear spin model. In particular, we realize the arising Backlund algebra in the form of an infinite-dimensional loop Lie algebra of the Kac-Moody type.This note is part of joint research work with E. Winterroth.__________Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 144, No. 1, pp. 153–161, July, 2005. 相似文献
939.
M. Majewski 《Journal of Optimization Theory and Applications》2006,128(3):635-651
In this paper, some results concerning the existence of optimal solutions to an optimal control problem are derived. The problem involves a quasilinear hyperbolic differential equation with boundary condition and a nonlinear integral functional of action. The assumption of convexity, under which the main theorem is proved, is not connected directly with the convexity of the functional of action. In the proof, the implicit function theorem for multimappings is used.Communicated by L. D. Berkovitz 相似文献
940.
A. V. Marshakov 《Theoretical and Mathematical Physics》2006,147(2):583-636
We consider the simplest gauge theories given by one-and two-matrix integrals and concentrate on their stringy and geometric
properties. We recall the general integrable structure behind the matrix integrals and turn to the geometric properties of
planar matrix models, demonstrating that they are universally described in terms of integrable systems directly related to
the theory of complex curves. We study the main ingredients of this geometric picture, suggesting that it can be generalized
beyond one complex dimension, and formulate them in terms of semiclassical integrable systems solved by constructing tau functions
or prepotentials. We discuss the complex curves and tau functions of one-and two-matrix models in detail.
[This article was written at the request of the Editorial Board. It is based on several lectures presented at schools of mathematical
physics and talks at the conference “Complex Geometry and String Theory” and the Polivanov memorial seminar.]
__________
Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 147, No. 2, pp. 163–228, May, 2006. 相似文献