基于ParetoHeu和实例化失败统计的关联启发式方法

变量排序启发式是约束规划求解约束满足问题中的一项关键技术,对求解效率有着重要影响。为进一步提高基于关联的变量排序启发式方法CRBS对问题求解的效率和能力,提出了一种基于ParetoHeu和实例化失败统计的关联启发式PICRBS。PICRBS采用源于帕累托最优的启发式组合方式ParetoHeu,将CRBS与经典的通用启发式dom/wdeg进行结合,同时加入基于实例化失败次数的权值统计方法,为问题求解选择最有可能导致搜索发生回溯的变量。实验结果显示,针对多个问题实例,该方法在问题求解效率上高于CRBS和主流变量排序启发式。     

The complexity of constraint satisfaction games and QCSP

We study the complexity of two-person constraint satisfaction games. An instance of such a game is given by a collection of constraints on overlapping sets of variables, and the two players alternately make moves assigning values from a finite domain to the variables, in a specified order. The first player tries to satisfy all constraints, while the other tries to break at least one constraint; the goal is to decide whether the first player has a winning strategy. We show that such games can be conveniently represented by a logical form of quantified constraint satisfaction, where an instance is given by a first-order sentence in which quantifiers alternate and the quantifier-free part is a conjunction of (positive) atomic formulas; the goal is to decide whether the sentence is true.While the problem of deciding such a game is PSPACE-complete in general, by restricting the set of allowed constraint predicates, one can obtain infinite classes of constraint satisfaction games of lower complexity. We use the quantified constraint satisfaction framework to study how the complexity of deciding such a game depends on the parameter set of allowed predicates. With every predicate, one can associate certain predicate-preserving operations, called polymorphisms. We show that the complexity of our games is determined by the surjective polymorphisms of the constraint predicates. We illustrate how this result can be used by identifying the complexity of a wide variety of constraint satisfaction games.     

最大度二元约束满足问题粒子群算法

约束满足问题是人工智能的一个重要研究领域,使用粒子群搜索算法来求解约束满足问题逐渐受到人们的重视.把变量的最大度静态变量序关系引入到评估函数中,区别对待每个变量,通过静态变量序关系改变适应度函数,从而影响算法对最优粒子的选择.使用随机约束满足问题实验表明,改进后的算法比原算法具有更好的搜索能力,能以更快的速度收敛到全局解.     

A Context for Constraint Satisfaction Problem Formulation Selection

Much research effort has been applied to finding effective ways for solving constraint satisfaction problems. However, the most fundamental aspect of constraint satisfaction problem solving, problem formulation, has received much less attention. This is important because the selection of an appropriate formulation can have dramatic effects on the efficiency of any constraint satisfaction problem solving algorithm.In this paper, we address the issue of problem formulation. We identify the heuristic nature of generating a good formulation and we propose a context for this process. Our work presents the research community with a focus for the many elements which affect problem formulation and this is illustrated with the example adding redundant constraints. It also provides a significant step towards the goal of automatic selection of problem formulations.     

一种量词约束满足问题的混合易解子类

量词约束满足问题是人工智能和自动推理领域的一个重要问题.寻找多项式时间易解子类,是研究此类问题计算复杂性的关键.通过分析二元量词约束满足问题中的约束关系特征,以及量词前缀中的全称量词排列的顺序,提出了针对全称量词变量子结构的易解性质的分析方法.通过该方法,扩展了已知的基于Broken-Triangle Property的多项式时间易解子类,提出了一个更一般化的量词约束满足问题的混合易解子类.讨论了易解子类在问题结构分析中的一个应用,即通过易解子类确定量词约束满足问题的隐蔽变量集合,并通过实验分析不同易解子类所确定的集合大小.实验改造了基于回溯算法的求解器,在回溯过程中加入了易解子类的识别算法,并采用随机约束满足问题的生成模型作为测试基准.通过对比实验,验证了提出的多项式时间易解子类可以识别出更小的隐蔽变量集合,因此,新提出的易解子类在确定隐蔽变量集合方面更具优势.最后阐述了其他已有的混合易解子类也可以通过类似方法进行扩展,从而得到更多的一般化的理论结果.     

求解入库堆垛问题的改进约束满足算法

入库堆垛问题普遍存在于堆场作业管理中,是在货物数目和出库顺序已知的前提下,要求较长（重）的货物置于较短（轻）的货物下方,目标是实现占用垛位数最少。通过问题分析,将其归结为一类带顺序约束的A形装箱问题,并建立了约束满足模型,设计了嵌入经典装箱启发式的约束满足求解算法。实验表明,该算法对于求解复杂约束下的大规模堆场问题较现有的装箱启发式有一定程度的改善。     

关系数据库设计中的数据依赖确定与语义分析

在关系数据库的设计中,数据依赖的确定是至关重要的,为保证数据的完整性,需要在数据库的设计、录入及维护全过程中保持数据依赖的一致性。数据依赖是关系数据间现实语义约束的一个反映,是属于语义范畴的,它的确定也是基于数据所蕴含的语义。本文结合实例,通过分析数据蕴含的语义,讨论确定关系数据的函数依赖和多值依赖的一般思路和方法,并分析了语义的强制与保持问题,对实际的关系数据库设计有理论参考价值。     

基于问题结构的启发式策略在析取时态问题求解中的应用

智能规划和调度中的许多时态(或时序)问题可以表达为析取时态问题(DTP).目前,多数析取时态问题求解器将析取时态问题看作约束可满足问题(CSP)或可满足问题(SAT),并使用标准的CSP(或SAT)技术来求解DTP.虽然这些技术在求解DTP时已经可以达到较好的效率,然而,文献中极少研究者关注利用DTP本身特殊的结构中隐含的信息来帮助DTP求解.尝试从DTP的拓扑结构中提取出一种启发式策略.这种启发式策略试图从DTP的结构中提取出定性和定量的标准(TVS)来选择优先赋给当前变量的值,同时基于这种定量值选择标准设计了一个动态变量选择策略(TVO).这种技术基于定义的一种DTP的图模型--析取时态网络(DTN).实验结果显示TVS和TVO策略均可以有效减小搜索中节点访问次数;同时它与已有的RSV值选择策略效果相当,而TVO优于最少剩余值(MRV)方法(节省一个数量级以上的访问节点数);此外,配合其他CSP启发技术,可以得到一个高效的DTP求解算法DTN-DTP.     

基于依存关系规则的汉语复句关系词自动识别

目前关于关系词自动识别的研究主要集中在分词的字面特征,并未涉及语法分析。本文在基于字面特征的关系词搭配的约束条件基础上,研究基于依存关系的约束条件。利用依存语法中依存关系的五条公理分析汉语复句中关系词搭配的依存关系,从中总结出7类约束条件,并把这7类约束条件形成依存关系规则加入规则库,运用字面特征与语法特征相结合的规则自动识别汉语复句关系词。实验结果表明,对关系词的识别率可以达到90%以上。     

Integrating multi-agent negotiation to resolve constraints in fulfilling supply chain orders

As the order fulfillment process (OFP) in supply chains shifts to outsourcing paradigm, the OFP performance relies on the coordination among supply chain partners to reach executable and effective plans. The coordination of OFP among supply chain partners can be viewed as a distributed constraint satisfaction problem (DCSP). This study adds the multi-agent negotiation mechanism to enhance the existing methods to solve the DCSP, and then evaluates the integrated system’s performance through experimentation on the OFP in the context of the metal industry. The experimental results show that the integrated system outperforms the existing distributed constraint satisfaction algorithms in various demand patterns.     

标准模型中可证安全的基于ID的身份认证方案

身份认证方案是一种非常重要和有用的密码学工具.给出了两个高效和可证安全的基于ID的身份认证方案,这两个认证方案都是由高效且在标准模型中基于强Diffie-Hellman假设可证安全的Boneh-Boyen签名方案衍生出来的.分析了这两个基于ID的身份认证方案的安全性,在标准模型中证明一个在被动攻击下防止冒充安全,另一个在主动和并行攻击下也防止冒充安全.     

On Parallel Partial Solutions and Approximation Schemes for Local Consistency in Networks of Constraints

A constraint network is arc consistent if any value of any of its variables is compatible with at least one value of any other variable. The Arc Consistency Problem (ACP) consists in filtering out values of the variables of a given network to obtain one that is arc consistent, without eliminating any solution. ACP is known to be inherently sequential, or P-complete, so in this paper we examine some weaker versions of it and their parallel complexity. We propose several natural approximation schemes for ACP and show that they are also P-complete. In an attempt to overcome these negative results, we turn our attention to the problem of filtering out values from the variables so that each value in the resulting network is compatible with at least one value of not necessarily all, but a constant fraction of the other variables. We call such a network partially arc consistent. We give a parallel algorithm that, for any constraint network, outputs a partially arc consistent subnetwork of it in sublinear ( O( logn)) parallel time using O(n²) processors. This is the first (to our knowledge) sublinear-time parallel algorithm with polynomially many processors that guarantees that in the resulting network every value is compatible with at least one value in at least a constant fraction of the remaining variables. Finally, we generalize the notion of partiality to the k-consistency problem.     

两个标准模型下门限签名方案的安全性分析

为了提高门限签名方案的计算效率,石贤芝等(2013年)和张建中等(2012年)分别提出了标准模型下高效的门限签名方案.对两个方案构造了两个有效的伪造攻击:攻击者在不知道用户的私钥情况下,可以伪造用户对任何消息的有效门限签名.最后分析了方案不安全的原因.     

强全序时态模式中混合依赖集成员籍问题的研究

对于TFD和RTMVD混合依赖集约束的强全序时态模式来说, 成员籍问题的解决对设计有效的模式分解算法必不可少.由于强全序时态模式中多时间粒度的使用,使其成员籍问题的解决变得更加复杂.为此定义了强全序时态模式下的属性集在给定时态类型上的混合闭包、属性集的混合闭包、属性集在给定时态类型上的混合依赖基、属性集的混合依赖基等概念,给出了求强全序时态模式下属性集的混合闭包、属性集的混合依赖基以及TFD和RTMVD混合依赖集成员籍问题的算法,并对算法的可终止性、正确性进行了证明,对时间复杂性进行了分析.     

网格环境下的分布仿真事件调度研究

针对网格仿真中的事件调度问题,提出一种新的时序管理方法。该方法同时考虑网格仿真成员的按需模型服务调用与成员间的交互,对仿真中具体存在的事件进行分类,建立成员的相关局部事件触发矩阵和时序关系矩阵,并应用Mutli-AWS算法求解每个事件的开始时间。实验结果证明,该方法可以确保成员之间事件的时序关系,有效解决成员按需模型服务调用问题。     

PMS故障树分析中的变量排序策略库研究

研究阶段任务系统(PMS)故障树变量排序方法。构造一个包含10种不同排序策略的策略库,基于实例基准测试对策略库中的单个策略进行平均性能分析,并在此基础上对策略库本身进行互补性和完备性分析。实例分析表明,应用该策略库可以为各种结构特征的大规模PMS故障树快速有效地生成系统二进制决策图。     

约束满足技术在板坯排序中的应用

热轧调度中的板坯排序问题是一类特殊的排序问题,具有约束条件复杂、NP难特点。为了简化问题,将板坯排序问题转化为一个约束满足问题处理。给出板坯排序问题的约束满足模型,设计了基于约束满足和启发式混合求解算法。用3组实际生产数据对算法性能进行验证,说明了算法的有效性。     

标准模型下高效的代理签名方案

代理签名方案允许原始签名者将自己的签名权力授权给代理签名者,使得代理签名者能够代表原始签名者对消息进行签名。提出了一个新的标准模型下可证安全的代理签名方案,其安全性基于q-强Diffie-Hellman困难问题,证明了该方案在标准模型下能够抵抗适应性选择消息攻击下的存在性伪造。与已有的方案进行比较,提出的方案需要较少的公共参数,实现了紧凑的安全归约,并且在密钥生成、标准签名、授权生成、代理签名生成等阶段具有较高的效率。     

Modeling Agent Negotiation Via Fuzzy Constraints in E-Business

In e-business, disputes between two or more parties arise for various reasons and involve different issues. Thus, resolution of these disputes frequently relies on some form of negotiation. This article presents a general problem-solving framework for modeling multi-issue multilateral agent negotiation using fuzzy constraints in e-business. Fuzzy constraints are thus used not only to define each agent's demands involving human concepts, but also to represent the relationships among agents. A concession strategy, based on fuzzy constraint-based problem-solving, is proposed to relax demands, and a trade-off strategy is presented to evaluate existing alternatives. This approach provides a systematic method for reaching an agreement that benefits all agents with a high satisfaction degree of constraints. Meanwhile, by applying the method, agents can move toward an agreement more quickly, because their search focuses only on the feasible solution space. An example application to negotiate an insurance policy among agents is provided to demonstrate the usefulness and effectiveness of the proposed framework.     

改进求解约束满足问题粗粒度弧相容算法

约束满足问题在人工智能领域有着广泛的应用.研究了约束满足问题的粗粒度维持弧相容求解算法,发现在求解过程中,对于指向已赋值变量的弧存在无效的修正检查,证明了这类修正检查是冗余的.提出一种方法避免这类冗余的修正检查,给出改进后的粗粒度弧相容算法的基本框架AC3_frame_ARR,该改进框架可用于改进所有粗粒度弧相容算法.实验结果表明,经过AC3_frame_ARR改进后的算法最多可以节省80%的修正检查次数和40%的求解耗时.