Computing Bisimulations for Finite-Controlπ-Calculus

Symbolic bisimulation avoids the infinite branching problem caused by instantiating input names with all names in the standard definition of bisimulation in π-calculus.However,it does not automatically lead to an efficient algorithm,because symbolic bisimulation is indexed by conditions on names,and directly manipulating such conditions can be computationally costly.In this paper a new notion of bisimulation is introduced,in which the manipulation of maximally consistent conditions is replaced with a systematic employment of schematic names.It is shown that the new notion captures symbolic bisimulation in a precise sense.Based on the new definition an efficient algorithm,which instantiates input names “on-the -fly“,is presented to check bisimulations for finite-control π-calculus.     

Calculi for Concurrent Processes

InmytalkIsurveyedsomeofthemainstreamresearchthathasbeendoneintheareaofprocesscalculiduringthelasttwentyyears-thoughfocusingonsomelastdevelopments,regardingespeciallymobilecomputing.IstartedwithabriefaccountofthepioneeringworkofMimerandhisco-workersonCCS,theCalculusofCommunicatingSystems.ThisbeguninthelateseventieswhenMimerrealizedthatScott'sdenotationalsemanticswasnotsofruitfulconcerningconcurrency.ApreliminarystepwastakenbyMilnerwithhisflowalgebra,consistingofasmallsetofoperationsandaxiom…     

A Crash Course in λ-Calculus

Thetalkpresentedthebasicresultsofλ-calculus.Aftergivingthesyntaxofterms(concretesyntax,abstractsyntaxusingdeBruijn'sindices)andthedefinitionofsubstitution,theβ-reductionrelation(strongreduction)ispresentedanditsmainpropertieslisted:.parallel-moveslemma,leadingtoconfluenceandtheChurch-Rosserpropertyofβ-conversion,anduniquenessofnormalforms.standardisationandthecompletenessofthenormalreductionstrategy(leftmost-outermost).finally,η-conversionisdiscussed,andtheseparabilityproperty(Bohmtheorem…     

The π-Calculus in Direct Style

We introduce a calculus which is a direct extension of both the and the calculi. We give a simple type system for it, that encompasses both Curry's type inference for the -calculus, and Milner's sorting for the -calculus as particular cases of typing. We observe that the various continuation passing style transformations for -terms, written in our calculus, actually correspond to encodings already given by Milner and others for evaluation strategies of -terms into the -calculus. Furthermore, the associated sortings correspond to well-known double negation translations on types. Finally we provide an adequate CPS transform from our calculus to the -calculus. This shows that the latter may be regarded as an assembly language, while our calculus seems to provide a better programming notation for higher-order concurrency. We conclude by discussing some alternative design decisions.     

X—演算与π—演算的语义比较研究

Through the comparison of syntactic structure,operational semantics and algebraic semantics between χ-calculus and π-calculus, this paper concludes that χ-calculus has more succinct syntactic structure,more explicit operational semantics,more intuitionistic algebraic semantics and more favorable algebraic property. And a translation from π-calculus to χ-calculus is presented.     

并发计算范型：CCS和π－演算

1 引言并发现象和并发系统在生活中随处可见:网络通信、移动电话系统、银行的信息流动、超市的物流系统都是典型的并发系统。所谓并发系统就是存在并发事件的系统。顺序计算是并发计算的特例,相比于并发计算是一个小得多的领域,其复杂性也小得多。函数被用来作为顺序计算的公共语义框架的基础。λ-演算就是一个著名的原型。一个顺序程序从语义上可以看作是一个从状态到状态的函数。例如顺序程序P1和P2:     

Symmetric cryptographic protocols for extended millionaires’ problem

Yao’s millionaires’ problem is a fundamental problem in secure multiparty computation, and its solutions have become building blocks of many secure multiparty computation solutions. Unfortunately, most protocols for millionaires’ problem are constructed based on public cryptography, and thus are inefficient. Furthermore, all protocols are designed to solve the basic millionaires’ problem, that is, to privately determine which of two natural numbers is greater. If the numbers are real, existing solutions do ...     

π-演算中无卫递归的消除

本文提出消除π－演算中无卫递归的公理，证明了将该公理加入到正则π－演算受卫递归子集上的证明系统后，所得到的证明系统在π－演算全体正则子集上关于互模拟等价的可靠性和完备性.     

任意位π的分段计算

本文提出了了一个采用矩阵扩大和矩阵分段方法，连续生成任意位π值的算法，并介绍了程序设计的关键技术和源程序。     

VHDL-AMS模拟中预定义属性的计算

VHDL－AMS是混合信号系统的行为级建模和模拟语言，其中预定义属性的计算是模拟的重要方面。讨论了计算所有新增属性的4种方法，简介了其中基本方法－－直接计算法和列方程计算法，重点介绍了列方程计算与直接计算的结合法和将属性转化为BLOCK语句计算的解决方法。大晒实验结果表明：文中方法可以高效、精确地计算语言新增的所有预定义属性。     

Topology in Process Calculus (Ⅰ):Limit Behaviour of Agents

This paper introduces the modifications on actions of a topology on names of actions and te simplest topology on agents induced by a topology on names of actions and shows that the limit behaviour of some agents is compatible with transitional semantics.     

Reaction Graph

The paper proposes reaction graphs as graphical representations of computational objects.A reaction graph is a directed graph with all its arrows and some of its nodes labeled.Computations are modled by graph rewriting of a simple nature.The basic rewriting rules embody the essence of both the communications among processes and cut-eliminations in proofs.Calculi of graphs are ideentified to give a formal and algebraic account of reaction graphs in the spirit of process algebra.With the help of the calculi,it is demonstrated that reaction graphs capture many interesting aspects of computations.     

TD—LAS技术实现新突破十八家通信企业联手推进产业化

在上海召开的“TD-LAS技术发展高层研讨会”后,更有包括中国普天、华为、中兴、首信北大方正在内的18家通信企业联名签署了建立产业联盟推进TD-LAS标准化、产业化的合作协议。     

高阶π-演算的互模拟理论研究

标签转移系统语义在早期的进程演算中取得了巨大的成功。基于标签转移系统，Milner与Park引入了互模拟的概念来描述进程间的等价性，互模拟从此成为整个进程演算中的理论基石。在经典的CCS进程演算中，标签转移系统用于描述进程的操作语义，然后在此基础上，互模拟概念通过如下方式被定义出来：两个进程若互模拟，不仅要满足任何一方的行为都要能够被另外一方匹配，同时要     

机群计算多通道通信技术研究与设计

讨论了提高机群系统通信性能的主要途径，详细分析了多通道通信技术的提出背景和相关技术，并提出了支持多路Myrinet网络并行通信的多通道通信技术设计方案MNC。     

Synchronization-Oriented Placement and Retrieval Strategies for Delay-Sensitive Media Streams

Multimedia data include text,image,audio and video,etc.Recent developments and advances in the areas of mass storage technology and high speed networks make it feasible for multimedia computing systems to offer services such as multimedia e-mial,teleconferencing and various vivid games.The storage and retrieval of multimedia data are two of the most important technologies in the futre multimedia systems.This paper analyzes the synchronization requirements of the delay-sensitive media streams,classifies the synchronization hierarchically and proposes several effective strategies for the intra-media and inter-media data placement problems.     

Process Calculifor Describing Distributed Systems

ProcessCalculi,suchasCCS~[1]orCSP~[2],weredesignedtodescribeandtoanalysecommunicat-ingsystems.Intuitivelywiththeselanguageasystemisdescribedintermsofasetofindependentprocesseswhichperiodicallysynchronisetheirbehaviourbyhand-shakecommunication.Thissyn-chronisationismodeledasthesimultaneousoccurrenceofanactiontogetherwithitscomplementaryaction,eachbeingperformedbyseparateindependentprocesses.Theseideaswerequicklyextendedtovalue-passingprocesses,wheretheideaofasynchronisationactionismademoreco…