基于等价关系的有穷自动机最小化方法

主要介绍了有穷自动机的基础知识,研究了有穷自动机的等价性,并在确定型有穷自动机的状态集上引入等价关系,给出了自动机的最小化过程。利用等价归并算法,可以将某一给定的确定型有穷自动机状态集上的等价状态归并掉．生成与其等价的最小化的确定型有穷自动机。     

基于等价关系的有穷自动机最小化方法

主要介绍了有穷自动机的基础知识,研究了有穷自动机的等价性,并在确定型有穷自动机的状态集上引入等价关系,给出了自动机的最小化过程。利用等价归并算法,可以将某一给定的确定型有穷自动机状态集上的等价状态归并掉,生成与其等价的最小化的确定型有穷自动机。     

几类带空转移的n元伪加权自动机的关系

引入了n元伪加权有穷自动机——带有n个有限字符集的伪加权有穷自动机、分明型n元伪加权有穷自动机和确定型n元伪加权有穷自动机的概念。根据状态转移函数在每个字符集上是否带空转移, 将以上自动机分为4类:带r-型空转移的n元伪加权有穷自动机和带空转移的n元伪加权有穷自动机和带r-型空转移的分明型n元伪加权有穷自动机和带空转移的分明型n元伪加权有穷自动机。给出了以上自动机所识别语言的定义并探究了它们之间的关系,讨论了状态转移函数在每个字符集上是否带空转移对其接受语言的影响。     

一类交替的ω—有穷自动机和确定的ω—有穷自动机识别能力…

本文提出了一类交替的ω－有穷自动机，即所有状态都是万能的交替的ω－有穷自动机，并采用了构造的方法证明了ω－ＵＡＦＡ和确定的ω－有穷自动机在四种接受条件下接受的ω－语言的等价性。     

由有穷自动机构造正则表达式的新算法

本文借助图论的理论，通过识别回路和不包含回路的由起始状态到终止状态的路径的方法，提出一种构造给定有穷自动机对应的正则表达式的新算法，并给出具体实例。     

基于紧凑型有穷自动机模型的告警相关处理

在网络管理领域,告警相关（Alarm Correlation)是取代简单告警过滤机构的一种全新故障管理策略。通过在非确定型有穷自动机在(ndfa)的定义中引入状态基(State Cardinality)的概念,本文首先给出紧凑型有穷自动机（cfa）的定义,然后提出了基于紧凑型有穷自动机的告警相关处理模型并进行了详尽的描述。在一个电信管理网（TMN）的故障管理子系统中应用该模型对大量的告警信息在时间上和空间上进行告警相关处理。仿真结果表明,基于紧凑型有穷自动机的告警相关处理模型的算法实现具备简单、高效、实用和实时的特点,尤其对并发故障具有较强的相关处理能力。     

基于改进BM算法的确定型有穷自动机的设计

通过对有穷自动机理论与BM算法进行分析,设计了一个基于改进BM算法的确定型有穷自动机的模型,该模型描述了向基于改进BM算法的确定型有穷自动机输入文本字符串,自动机输出TRUE,说明文本串中存在与模式串相匹配的字符;自动机输出FALSE,说明文本串中不存在与模式串相匹配的字符串,并给出了对比实验及分析.     

一类交替的ω－有穷自动机和确定的ω－有穷自动机识别能力的等价性

本文提出了一类交替的ω－有穷自动机，即所有状态都是万能的交替的ω－有穷自动机（记为ω－ＵＡＦＡ），并采用了构造的方法证明了ω－ＵＡＦＡ和确定的ω－有穷自动机在四种接受条件下接受的ω－语言的等价性。     

论有穷状态验证方法的局限性

程序有穷状态验证方法是介于程序验证和程序测试之间的一种方法，一方面它如同程序验证一样可以证明某程序具有某些要求的性质，或找出反例证明该程序不具有所要求的性质。另一方面它又不像程序验证那样复杂，要求验证人员具有较高的形式化推理的专业理论和数学水平。但是，现有的有穷状态验证方法有很大的局限性，它要求所论证的性质是有穷自动机所接受的事件序列的集合，或等价地说该性质能表示成为正则表达式。众所周知，有穷自动机所能接受的语言类，按Chomsky字的集合的分类是很小的类。本文讨论了这种局限性，井尝试突破只能使用有穷自动机的限制，提出了一种新的验证方法——有穷路径验证法。在这种方法中，所论证的性质表示可以推广到使用任何一类自动机。作为代价，描写系统的模型限制是无环的。对于有环的描写系统的模型，本文提出了一种称之为“有穷路径测试”的方法。同一般的程序测试一样，用这种方法通过测试不能正面地验证程序的正确性，可是如果通不过测试，则能帮你发现反例，找出程序的错误。与一般的程序测试不同的是这里的测试是相对于模型的路径，而不执行实际的程序。     

论回溯自动机

为了描述集成化软件工程环境用户接口中选单的控制机构,需要引入回溯自动机的概念。本文给出了回溯自动机概念的严格数学定义,并讨论了它与有穷自动机、确定的下推自动机等之间的关系,证明了它所接受的语言类处于正则语言类与确定的上下文无关语言类之间。     

An approximation algorithm for state minimization in 2-MDFAs

In this paper, we analyze the problem of state minimization in a class of Finite State Automata called Two Start State Deterministic Finite State Automata (2-MDFAs). A 2-MDFA is similar to a deterministic finite state automaton (DFA), in that on a given input, each state has precisely one destination state; however, it differs from a DFA in that there are two start states. A string is accepted by a 2-MDFA if and only if there exists a transitional path from either start state to a finish state, on that string. Observe that 2-MDFAs provide a limited amount of non-determinism and hence investigating their properties from the perspective of state minimization is a worthwhile pursuit. In case of unbounded non-determinism, i.e., Non-deterministic finite state automata (NFAs), it is well-known that the state minimization problem is PSPACE-complete [Jiang and Ravikumar in Proceedings of the 18th International Colloquium on Automata, Languages and Programming, ICALP’91, Madrid, Spain, July 8–12, 1991] and further that such automata can be exponentially more succinct than DFAs [Meyer and Fischer in Proceedings of the 12th SWAT(Annual Symposium on switching and automata theory), pp 188-191, 1971]. Even in the case of 2-MDFAs, the minimization problem remains non-trivial; indeed, Malcher in Theor Comput Sci 327(3):375–390, 2004 shows that the corresponding decision problem is NP-complete. We focus on deriving approximability bounds for the state minimization problem in 2-MDFAs. Our main contribution in the current paper, is the design of an n-approximation algorithm for state minimization in 2-MDFAs, where n denotes the minimum number of states required to represent the input language as a 2-MDFA. We also present a proof that this bound is tight for our algorithm.The work of K. Subramani was supported in part by the Air-Force office of Scientific Research under Grant FA9550-06-1-0050     

Weighted tree automata and weighted logics

We define a weighted monadic second order logic for trees where the weights are taken from a commutative semiring. We prove that a restricted version of this logic characterizes the class of formal tree series which are accepted by weighted bottom-up finite state tree automata. The restriction on the logic can be dropped if additionally the semiring is locally finite. This generalizes corresponding classical results of Thatcher, Wright, and Doner for tree languages and it extends recent results of Droste and Gastin [Weighted automata and weighted logics, in: Automata, Languages and Programming—32nd International Colloquium, ICALP 2005, Lisbon, Portugal, 2005, Proceedings, Lecture Notes in Computer Science, Vol. 3580, Springer, Berlin, 2005, pp. 513–525, full version in Theoretical Computer Science, to appear.] from formal power series on words to formal tree series.     

Structure of weakly invertible semi-input-memory finite automata with delay 2

Semi-input-memory finite automata,a kind of finite automata introduced by the author of this paper for studying error propagation,are a generalization of input-memory finite automata by appending an autonomous finite automaton component.This paper gives a characterization on the structure of weakly invertible semi-input-memory finite automata with delay 2 in which input alphabets and output alphabets have two elements and autonomous finite automata are cyclic.For the structure of feedforward inverse finite automata with delay 2,Zhu first gave a characterization;from a result on mutual invertibility of finite automata,the result mentioned above also leads to a different characterization on the structure of feedforward result mentioned above also leads to a different characterization on the structure of feedforward inverse finite automata with delay 2.     

有限自动机可识别语言的基数

利用有向图的邻接矩阵研究有限自动机的可识别语言的基数问题。通过建立有限自动机的可识别语言与其有向图中从初始结点（有限自动机的初始状态）到终止结点（有限自动机的终止状态）的路的一一对应关系,利用邻接矩阵给出了有限自动机的可识别语言的基数公式,研究了两个自动机不等价的充分条件。     

Links between probabilistic automata and hidden Markov models: probability distributions, learning models and induction algorithms

This article presents an overview of Probabilistic Automata (PA) and discrete Hidden Markov Models (HMMs), and aims at clarifying the links between them. The first part of this work concentrates on probability distributions generated by these models. Necessary and sufficient conditions for an automaton to define a probabilistic language are detailed. It is proved that probabilistic deterministic automata (PDFA) form a proper subclass of probabilistic non-deterministic automata (PNFA). Two families of equivalent models are described next. On one hand, HMMs and PNFA with no final probabilities generate distributions over complete finite prefix-free sets. On the other hand, HMMs with final probabilities and probabilistic automata generate distributions over strings of finite length. The second part of this article presents several learning models, which formalize the problem of PA induction or, equivalently, the problem of HMM topology induction and parameter estimation. These learning models include the PAC and identification with probability 1 frameworks. Links with Bayesian learning are also discussed. The last part of this article presents an overview of induction algorithms for PA or HMMs using state merging, state splitting, parameter pruning and error-correcting techniques.     

Structure of Weakly Invertible Semi-Input-Memory Finite Automata with Delay 1

Semi-input-memory finite automata,a kind of finite automata introduced by the first author of this paper for studying error propagation ,are a generalization of inputmemory finite automata ,by appending an autonomous finite automation component .In this paper,we give a characterization of the structure of weakly invertible semi-input-memory finite automata with delay 1,in which the state graph of each autonomous finite automation is cycle,From a result on mutual invertibility of finite automata obtained by th authors recently,it leads to a characerization of the structure of feedfoward inverse finite automata with delay 1.     

Input-trees of finite automata and application to cryptanalysis

In this paper,Weights of output set and of input set for finite automata are discussed.For a weakly invertible finite automaton,we prove that for states with minimal output weight,the distruibution of input sets is uniform.Then for a kind of compound finite automata,we give weights of output set and of input set explicitly,and a characterization of their input-trees.For finite automaton public key cryptosystems,of which automata in public keys belong to such a kind of compound finite automata,we evaluate search amounts of exhaust search algorithms in average case and in worse case for both encryption and signature,and success ful probabilities of stochastic search algorithms for both encryption and signature.In addition,a result on mutual invertibility of inite automata is also given.     

基于有限状态自动机的服务组合模型

分析了目前服务计算的研究现状和存在的问题，在D Berardi和A Wombacher的基础上提出了一种带条件的有限状态自动机模型cFSA（Finite State Automata with condition），并给出了基于cFSA的服务理论模型．在该服务理论模型的基础上提出了一种基于有限状态自动机的服务组合形式化模型，并给出了该模型的代数性质和实现方法．     

Binding-blocking automata

We propose an automaton model called as binding-blocking automaton (BBA). It is a finite state automaton together with the ability to block some symbols and postpone them for reading by the head at a later time. The idea of blocking some symbols from being read by the head and unblocking when the system requires to read is motivated by peptide computing where some parts of peptide sequences are blocked by attaching an antibody with higher affinity and unblocked at a later point by the removal of the appropriate antibody. We study the variants of such systems, analyse the power of each variants and show various hierarchy results involving them. We also define normal-forms of binding-blocking automata for one of its variants and also show that the acceptance power of this variant of BBA is strictly less than that of multi-head finite automata.     

Semi-tensor product of matrices approach to reachability of finite automata with application to language recognition

This paper investigates the transition function and the reachability conditions of finite automata by using a semitensor product of matrices, which is a new powerful matrix analysis tool. The states and input symbols are first expressed in vector forms, then the transition function is described in an algebraic form. Using this algebraic representation, a sufficient and necessary condition of the reachability of any two states is proposed, based on which an algorithm is developed for discovering all the paths from one state to another. Furthermore, a mechanism is established to recognize the language acceptable by a finite automaton. Finally, illustrative examples show that the results/algorithms presented in this paper are suitable for both deterministic finite automata (DFA) and nondeterministic finite automata (NFA).