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In mathematics, the Bernoulli scheme or Bernoulli shift is a generalization of the Bernoulli process to more than two possible outcomes.〔P. Shields, ''The theory of Bernoulli shifts'', Univ. Chicago Press (1973)〕〔Michael S. Keane, "Ergodic theory and subshifts of finite type", (1991), appearing as Chapter 2 in ''Ergodic Theory, Symbolic Dynamics and Hyperbolic Spaces'', Tim Bedford, Michael Keane and Caroline Series, Eds. Oxford University Press, Oxford (1991). ISBN 0-19-853390-X〕 Bernoulli schemes are important in the study of dynamical systems, as most such systems (such as Axiom A systems) exhibit a repellor that is the product of the Cantor set and a smooth manifold, and the dynamics on the Cantor set are isomorphic to that of the Bernoulli shift.〔Pierre Gaspard, ''Chaos, scattering and statistical mechanics''(1998), Cambridge University press〕 This is essentially the Markov partition. The term ''shift'' is in reference to the shift operator, which may be used to study Bernoulli schemes. The Ornstein isomorphism theorem shows that Bernoulli shifts are isomorphic when their entropy is equal. ==Definition== A Bernoulli scheme is a discrete-time stochastic process where each independent random variable may take on one of ''N'' distinct possible values, with the outcome ''i'' occurring with probability , with ''i'' = 1, ..., ''N'', and : The sample space is usually denoted as : as a shorthand for : The associated measure is called the Bernoulli measure : The σ-algebra on ''X'' is the product sigma algebra; that is, it is the (countable) direct product of the σ-algebras of the finite set . Thus, the triplet : is a measure space. A basis of is the cylinder sets. Given a cylinder set , its measure is : The equivalent expression, using the notation of probability theory, is : for the random variables The Bernoulli scheme, as any stochastic process, may be viewed as a dynamical system by endowing it with the shift operator ''T'' where : Since the outcomes are independent, the shift preserves the measure, and thus ''T'' is a measure-preserving transformation. The quadruplet : is a measure-preserving dynamical system, and is called a Bernoulli scheme or a Bernoulli shift. It is often denoted by : The ''N'' = 2 Bernoulli scheme is called a Bernoulli process. The Bernoulli shift can be understood as a special case of the Markov shift, where all entries in the adjacency matrix are one, the corresponding graph thus being a clique. 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Bernoulli scheme」の詳細全文を読む スポンサード リンク
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