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arXiv 0909.1647cs.LO
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概率加权自动机

Probabilistic Weighted Automata

Krishnendu Chatterjee, Laurent Doyen, Thomas A. Henzinger

摘要:

不确定加权自动机是在变迁上具有数值权重的有限自动机。它们定义了数量语言L,给每个词w分配一个实数L(w)。无限词w的值被计算为w上所有游程的最大值,游程的值被计算为最大值、limsup、liminf、极限平均值或转换权重的折扣和。我们引入了概率加权自动机,其中以随机(而不是非确定性)方式选择转换。在几乎肯定语义(分别)。正语义),则单词w的值是最大实数v,使得在w上的游程具有至少为v的值,概率为1(分别为正概率)。我们研究了概率加权自动机的自动机理论的经典问题:空性和普遍性,表达性,以及在各种语言操作下的封闭性。对于数量语言,空性和普遍性被定义为一些(分别)的值是否。每一个)字都超过了给定的阈值。我们证明了这些问题中的一些是可判定的,而另一些是不可判定的。关于表达能力,我们表明,概率使我们能够定义各种各样的新类的定量语言,除了贴现和自动机,概率的选择是没有更多的表达比非确定性。最后,我们给出了一个几乎完整的图片封闭的概率加权自动机的各种类以下逐点操作的定量语言:最大值,最小值,总和,和数值补。

英文摘要:

Nondeterministic weighted automata are finite automata with numerical weights on transitions. They define quantitative languages L that assign to each word w a real number L(w). The value of an infinite word w is computed as the maximal value of all runs over w, and the value of a run as the maximum, limsup, liminf, limit average, or discounted sum of the transition weights. We introduce probabilistic weighted automata, in which the transitions are chosen in a randomized (rather than nondeterministic) fashion. Under almost-sure semantics (resp. positive semantics), the value of a word w is the largest real v such that the runs over w have value at least v with probability 1 (resp. positive probability). We study the classical questions of automata theory for probabilistic weighted automata: emptiness and universality, expressiveness, and closure under various operations on languages. For quantitative languages, emptiness and universality are defined as whether the value of some (resp. every) word exceeds a given threshold. We prove some of these questions to be decidable, and others undecidable. Regarding expressive power, we show that probabilities allow us to define a wide variety of new classes of quantitative languages, except for discounted-sum automata, where probabilistic choice is no more expressive than nondeterminism. Finally, we give an almost complete picture of the closure of various classes of probabilistic weighted automata for the following pointwise operations on quantitative languages: max, min, sum, and numerical complement.

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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