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arXiv math/0506417math.DS
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一维元胞自动机中缺陷粒子的运动学

Defect Particle Kinematics in One-Dimensional Cellular Automata

Marcus Pivato

摘要:

设A^Z是有限字母表A中双无穷序列的Cantor空间,σ是A^Z上的移位映射.一个“元胞自动机”是A^Z的一个连续的、sigma-可换的自映射Phi,而一个“Phi-不变子移位”是A^Z的一个闭的、(Phi,sigma)-不变子集X。假设x是A^Z中的一个序列,除了我们称之为“defect”的一个小区域外,它在任何地方都是X-容许的。根据经验观察到,这种缺陷在Φ迭代下持续存在,并且经常像“粒子”一样传播。我们的特点,这些粒子的运动,并表明,它属于几个制度,从简单的确定性运动,广义随机游动,复杂的运动仿真图灵机或下推自动机。一个结果是,一些关于缺陷行为的问题在形式上是不可判定的。

英文摘要:

Let A^Z be the Cantor space of bi-infinite sequences in a finite alphabet A, and let sigma be the shift map on A^Z. A `cellular automaton' is a continuous, sigma-commuting self-map Phi of A^Z, and a `Phi-invariant subshift' is a closed, (Phi,sigma)-invariant subset X of A^Z. Suppose x is a sequence in A^Z which is X-admissible everywhere except for some small region we call a `defect'. It has been empirically observed that such defects persist under iteration of Phi, and often propagate like `particles'. We characterize the motion of these particles, and show that it falls into several regimes, ranging from simple deterministic motion, to generalized random walks, to complex motion emulating Turing machines or pushdown automata. One consequence is that some questions about defect behaviour are formally undecidable.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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