STGA的变种及其互模拟验证

为刻画和验证无穷值域上的传值进程，Ｈｅｎｎｅｓｓｙ和Ｌｉｎ先后提出符号迁移图（ＳＴＧ）和带赋值符号迁移图（ＳＴＧＡ）作为传值进程的语义表示模型，并给出了相应的强互模拟算法．为将该方法推广至实际应用中更常用的弱互模拟等价和观察同余的验证问题，该文首先引入了ＳＴＧＡ的一个变种，它与原模型的不同之处在于将符号迁移上赋值和符号动作的执行次序颠倒，因而可定义些种ＳＴＧＡ结果间的符号双迁移关系．文中提出了从正     

带赋值符号迁移图的局部优化算法

带赋值符号迁移图（ＳＴＧＡ）是刻画一般传值进程的抽象计算模型,在ＳＴＧＡ上可以用“ｏｎ－ｔｈｅ－ｆｌｙ”实例化算法来验证传值进程之间的互模拟等价。由于ＳＴＧＡＡ的一个结点对应于具体迁移图的许多结点,在ＳＴＧＡ上所作的优化对提高互模拟判定算法的时间和空间效率会产生很大的影响。     

基于符号迁移图的互模拟验证算法

符号迁移图是传值进程的一种直观而简洁的语义表示模型，该模型由Hennessy和Lin首先提出，随后又被Lin推广至带赋值的符号迁移图，本文不但定义了符号迁移图各种版本（基／符号）的强操作语义和强互模拟，提出了相互的强互模拟算法，而且通过引入符号观察图和符号同余图，给出了其弱互模拟等价和观察同余的验证算法，给出并证明了了τ－循环和τ－边消去定理，在应用任何弱互模拟观察同余验证算法之前，均可利用这些定理对所给符号迁移图进行化简。     

嵌套谓词等式系与弱互模拟

带赋值符号迁移图是一般传值进程的语义模型,其强互模拟等价可以归结为谓词等式系的最大解.该文将这一结果推广到弱互模拟等价,为此,引入嵌套谓词等式系的概念,并提出算法,将带赋值符号迁移图的弱互模拟等价归结为形如E₂μE₁的嵌套谓词等式系的最大解.     

带复杂数据结构的模型检测工具

模型检测是近二十几年来最成功的自动验证技术之一，而模型检测工具的开发是将模型检测和实际相结合的关键．为了有效地对涉及到复杂数据类型的并发传值系统进行模型检测，总结了以扩展的带赋值符号迁移图和模态图分别作为并发系统和逻辑公式的语义模型来实现模型检测工具的工作，特别是将复杂数据结构引入传值进程定义语言和带赋值符号迁移图．同时结合实际例子说明模型检测工具的有效性．     

数据传送进程的符号互模拟*

本文提出数据传送进程的符号迁移语义，引入符号互模拟的概念，证明了两个进程在传统意义下互模拟当且仅当它们符号互模拟．由于无穷域上的数据传送进程的传统迁移图是无穷的，而其中相当一部分的符号迁移图是有穷的，文章的结果为在有穷时间和空间内判定这类进程的互模拟关系开辟了可能性．     

数据传送进程的符号互模拟

本提出数据传送进程的符号迁移语义，引入符号互模拟的概念，证明了两个进程在传统意义下互模拟当且仅当它们符号互模拟。我穷域上的数据传送进程的传统迁移图是无穷的而其中相当的一部分的符号迁移图是有穷的，章的结果为在有穷时间和空间内判定这类进程的互模拟关系开辟了可能性。     

面向传值进程的谓词μ-演算与FO(HML)的完备推演系统

作者提出一个谓词μ－演算系统，目的在于描述传值进程的性质，该系统的公式和谓词相互递归定义，谓词中含有抽象式，谓词变元以及最大和最小不动点，其语义模型是带赋值的符号迁移图所诱导的迁移系统，并且该系统包含Hennessy-Milner逻辑的一阶扩弃FO（HML）作为子系统，作者用例说明了本演算系统在表达传值进程性质方面的优越性，该文后半部分主要给出了FO（HML）的一个推演系统，并运用判定树（Tableau)的方法，证明了所给出了推演系统是完备的。     

时间符号迁移图及其互模拟判定

引入时间符号迁移图的概念，作为既涉及通讯又具有实时性的并发系统的模型，该文给出了这种迁移图时间互模拟的算法，并证明了该算法的正确性。     

面向实时传值系统的局部模型检测

为对实时传值系统进行模型检测，本文给出了时间符号迁移图作为系统的建模语言，以及实时谓词μ演算作为刻画性质的逻辑语言。本文给出了基于时间符号迁移图和实时谓词μ演算的一个模型检测算法，该算法动态生成和检测可达的状态空间，并且采用对数据变量on—the—fly实例化以及动态切分时间计值集合的方法，是一个局部算法。该算法不仅能处理基于有限域的变量，还可处理一类数据域无穷的变量(称“数据无关”变量)。     

Probabilistic bisimulations for quantum processes

Modeling and reasoning about concurrent quantum systems is very important for both distributed quantum computing and quantum protocol verification. As a consequence, a general framework formally describing communication and concurrency in complex quantum systems is necessary. For this purpose, we propose a model named qCCS. It is a natural quantum extension of classical value-passing CCS which can deal with input and output of quantum states, and unitary transformations and measurements on quantum systems. The operational semantics of qCCS is given in terms of probabilistic labeled transition system. This semantics has many different features compared with the proposals in the available literature in order to describe the input and output of quantum systems which are possibly correlated with other components. Based on this operational semantics, the notions of strong probabilistic bisimulation and weak probabilistic bisimulation between quantum processes are introduced. Furthermore, some properties of these two probabilistic bisimulations, such as congruence under various combinators, are examined.     

A Higher-Order Calculus for Graph Transformation

This paper presents a formalism for defining higher-order systems based on the notion of graph transformation (by rewriting or interaction). The syntax is inspired by the Combinatory Reduction Systems of Klop. The rewrite rules can be used to define first-order systems, such as graph or term-graph rewriting systems, Lafont's interaction nets, the interaction systems of Asperti and Laneve, the non-deterministic nets of Alexiev, or a process calculus. They can also be used to specify higher-order systems such as hierarchical graphs and proof nets of Linear Logic, or to specify the operational semantics of graph-based languages.     

A Coinduction Principle for Recursive Data Types Based on Bisimulation

The concept of bisimulation from concurrency theory is used to reason about recursively defined data types. From two strong-extensionality theorems stating that the equality (resp. inequality) relation is maximal among all bisimulations, a proof principle for the final coalgebra of an endofunctor on a category of data types (resp. domains) is obtained. As an application of the theory developed, an internal full abstraction result (in the sense of S. Abramsky and C.-H. L. Ong [Inform. and Comput.105, 159–267 (1993)] for the canonical model of the untyped call-by-valueλ-calculus is proved. Also, the operational notion of bisimulation and the denotational notion of final semantics are related by means of conditions under which both coincide.     

O-Minimal Hybrid Systems

An important approach to decidability questions for verification algorithms of hybrid systems has been the construction of a bisimulation. Bisimulations are finite state quotients whose reachability properties are equivalent to those of the original infinite state hybrid system. In this paper we introduce the notion of o-minimal hybrid systems, which are initialized hybrid systems whose relevant sets and flows are definable in an o-minimal theory. We prove that o-minimal hybrid systems always admit finite bisimulations. We then present specific examples of hybrid systems with complex continuous dynamics for which finite bisimulations exist. Date received: June 9, 1998. Date revised: June 28, 1999.     

Language-based Performance Prediction for Distributed and Mobile Systems

We present a framework for performance prediction of distributed and mobile systems. We rely on process calculi and their structural operational semantics. The dynamic behaviour is described through transition systems whose transitions are labelled by encodings of their proofs that we then map into stochastic processes. We enhance related works by allowing general continuous distributions resorting to a notion of enabling between transitions. We also discuss how the number of resources available affects the overall model. Finally, we introduce a notion of bisimulation that takes stochastic information into account and prove it to be a congruence. When only exponential distributions are of interest our equivalence induces a lumpable partition on the underlying Markov process.     

Towards a theory of mathematical operational semantics

Turi and Plotkin gave a precise mathematical formulation of a notion of structural operational semantics in their paper “Towards a mathematical operational semantics.” Starting from that definition and at the level of generality of that definition, we give a mathematical formulation of some of the basic constructions one makes with structural operational semantics. In particular, given a single-step operational semantics, as is the spirit of their work, one composes transitions and considers streams of transitions in order to study the dynamics induced by the operational semantics. In all their leading examples, it is obvious that one can do that and it is obvious how to do it. But if their definition is to be taken seriously, one needs to be able to make such constructions at the level of generality of their definition rather than case-by-case. So this paper does so for several of the basic constructions associated with structural operational semantics, in particular those required in order to speak of a stream of transitions and hence of dynamics.