Communications in information and systems 

About: Communications in information and systems is an academic journal published by International Press of Boston, Inc.. The journal publishes majorly in the area(s): Nonlinear system & Computer science. It has an ISSN identifier of 1526-7555. Over the lifetime, 331 publications have been published receiving 6564 citations.

Large population stochastic dynamic games: closed-loop McKean-Vlasov systems and the Nash certainty equivalence principle

Abstract: We consider stochastic dynamic games in large population conditions where multiclass agents are weakly coupled via their individual dynamics and costs. We approach this large population game problem by the so-called Nash Certainty Equivalence (NCE) Principle which leads to a decentralized control synthesis. The McKean-Vlasov NCE method presented in this paper has a close connection with the statistical physics of large particle systems: both identify a consistency relationship between the individual agent (or particle) at the microscopic level and the mass of individuals (or particles) at the macroscopic level. The overall game is decomposed into (i) an optimal control problem whose Hamilton-Jacobi-Bellman (HJB) equation determines the optimal control for each individual and which involves a measure corresponding to the mass effect, and (ii) a family of McKean-Vlasov (M-V) equations which also depend upon this measure. We designate the NCE Principle as the property that the resulting scheme is consistent (or soluble), i.e. the prescribed control laws produce sample paths which produce the mass effect measure. By construction, the overall closed-loop behaviour is such that each agent’s behaviour is optimal with respect to all other agents in the game theoretic Nash sense.

Network Error Correction, I: Basic Concepts and Upper Bounds

Abstract: Error correction in existing point-to-point communication networks is done on a link-by-link basis, which is referred to in this paper as classical error correction. Inspired by network coding, we introduce in this two-part paper a new paradigm called network error correction .T he theory thus developed subsumes classical algebraic coding theory as a special case. In Part I, we discuss the basic concepts and prove the network generalizations of the Hamming bound and the Singleton bound in classical algebraic coding theory. By studying a few elementary examples, the relation between network error correction and classical error correction is investigated.

Failures of Adaptive Control Theory and Their Resolution

Abstract: Adaptive control is a very appealing technology, at least in principle. Yet its use has been conditioned by an attitude of distrustfulness on the part of some practitioners. In this paper, we explain why such distrustfulness is warranted, by reviewing a number of adaptive control approaches which have proved deficient for some reason that has not been immediately apparent. The explanation of the deficiencies, which normally were reflected in unexpected instabilities, is our main concern. Such explanations, coupled with remedies for avoiding the deficiencies, are necessary to engender confidence in the technology. These include the unpredictable failure of the MIT rule; the bursting phenomenon, and how to prevent it; the Rohrs' counterexample, which attempted to disqualify all adaptive control algorithms; the notion that identification of a plant is only valid conceptually for a restricted range of controllers (with the implication that in adaptive control, certain controller changes suggested by adaptive control algorithms may introduce instability); and the concept of multiple model adaptive control. 1. Introduction. Adaptive controllers are a fact of life, and have been for some decades. However, theory and practice have not always tracked one another. In this paper, we examine several instances of such a mismatch. These are: • The MIT rule, an intuitively based gradient descent algorithm that gave unpredictable performance; satisfactory explanation of performance started to become possible in the 1980s. • Bursting, a phenomenon of temporary instability in adaptive control algo- rithm implementation of a type observed in the 1970s; explanation and our understanding of avoidance mechanisms only became possible in the 1980s. • The Rohrs' counterexample, which argued that adaptive control laws existing at the time could not be used with confidence in practical designs, because unmodeled dynamics in the plant could be excited and yield an unstable control system. • Iterative controller re-design and identification, an intuitively appealing ap- proach to updating controllers that came to prominence in the 1980s and 1990s, and which can lead to unstable performance. Explanation and an understanding of an avoidance mechanism came around 2000. • Multiple model adaptive control, another intuitively appealing approach to adaptive control with the potential to include non-linear systems. It too can lead to unstable performance; early theoretical development left untouched important issues of the number of controllers to be used, and their location

Network Error Correction, II: Lower Bounds

Abstract: In Part I of this paper, we introduced the paradigm of network error correction as a generalization of classical link-by-link error correction. We also obtained the network generalizations of the Hamming bound and the Singleton bound in classical algebraic coding theory. In Part II, we prove the network generalization of the Gilbert-Varshamov bound and its enhancement. With the latter, we show that the tightness of the Singleton bound is preserved in the network setting. We also discuss the implication of the results in this paper.