An Eclipse-based Integrated Environment for Developing Executable Structural Operational Semantics Specifications

The Structural Operational Semantics Development Tooling (SOSDT) Eclipse Plugin integrates the Relational Meta-Language (RML) compiler and debugger with the Eclipse Integrated Development Environment Framework. SOSDT, together with the RML compiler and debugger, provides an environment for developing and maintaining executable Structural Operational Semantics specifications, including the Natural Semantics big step variant of SOS specifications. The RML language is successfully used at our department for writing large specifications for a range of languages like Java, Modelica, Pascal, MiniML etc. The SOSDT environment includes support for browsing, code completion through menus or popups, code checking, automatic indentation, and debugging of specifications.     

Well-behaved Translations between Structural Operational Semantics

We examine two versions of maps between distributive laws as candidates for well-behaved translations between structural operational semantics, and validate that by using simple coalgebraic arguments. We give some concrete examples of well-behaved translations that are maps between distributive laws. The modelling of structural operational semantics uses Turi and Plotkin's categorical models of GSOS. These maps between distributive laws come from the previous work on 2-categories of distributive laws.     

基于逻辑的软件演化操作语言及结构化操作语义

由于使用环境和新技术的不断变化,软件演化的控制变得日趋复杂.为了提高软件演化活动的可视化和形式化支持程度,结合谓词逻辑和软件演化,提出了一种软件演化操作语言SEOL(Software Evolution Operational Language)描述软件演化,给出了SEOL的语法和结构化操作语义描述,并指出了软件演化操作语义等价分析方法.结合软件代码演化和软件模型演化实例,说明了SEOL的应用.与已有的软件演化操作描述相比,SEOL在易用性、可重用性和形式化分析方面有明显的改善,为软件演化的管理、分析和实施奠定了基础.     

Bi-inductive Structural Semantics: (Extended Abstract)

We propose a simple order-theoretic generalization of set-theoretic inductive definitions. This generalization covers inductive, co-inductive and bi-inductive definitions and is preserved by abstraction. This allows the structural operational semantics to describe simultaneously the finite/terminating and infinite/diverging behaviors of programs. This is illustrated on the structural bifinitary small/big-step trace/relational/operational semantics of the call-by-value λ-calculus.     

一种适于硬件实现的快速模乘算法

RSA算法是目前应用最广泛的一种公钥加密算法,随着人们对加密安全性和加密速度要求的提高,硬件实现加密算法成了密码学应用的一个趋势。模乘算法是模幂算法的核心,基于Montgomery算法,结合Booth2算法的思想,文章给出了一种改进的高效算法,并且通过FPGA实现。对该算法和参考文献中算法的性能进行了比较,可以看出这一改进算法在速度和面积上优于现有的算法。     

Formal Foundations of Operational Semantics

In this paper we report on the results of a sophisticated and substantial use of PVS to establish a recent result in operational semantics. The result we establish is a context lemma for operational equivalence for very wide class of programming languages, known as the CIU theorem. The proof uses the annotated holes technique to represent contexts and compute with them. Thus this paper demonstrates that that it is possible to use PVS as a tool in the development of modern operational techniques, and a productive tool at that. The process of formalizing the CIU theorem revealed several gaps in published proof. The proof of the CIU theorem in PVS took approximately six months to develop. The actual machine checked proof involves the proving of around one thousand facts, and takes PVS slightly less than three hours of CPU time running on a Linux machine configured with 2 GBytes of main memory and four 550 MHz Xeon PIII processors.     

Modular robotic tiles: experiments for children with autism

We developed a modular robotic tile and a system composed of a number of these modular robotic tiles. The system composed of the modular robotic tiles engages the user in physical activities, e.g., physiotherapy, sports, fitness, and entertainment. The modular robotic tiles motivate the user to perform physical activities by providing immediate feedback based upon their physical interaction with the system. With the modular robotic tiles, the user is able to make new physical set-ups within less than a minute. The tiles are applicable for different forms of physical activities (e.g., therapeutic rehabilitation), and with the proper radio communication mechanism they may give unique possibilities for documentation of the physical activity (e.g., therapeutic treatment). A major point of concern in modular robotics is the connection mechanism, so we investigated different solutions for the connection between the modules, and outline their pros and cons for utilizing modules with different connection mechanisms as different kinds of playware. This kind of playware is highly motivating because of its immediate feedback and fun, interesting games. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Trace-Based Abstract Interpretation of Operational Semantics

We present trace-based abstract interpretation, a unification of severallines of research on applying Cousot-Cousot-style abstract interpretation a.i. tooperational semantics definitions (such as flowchart, big-step, and small-step semantics)that express a programs semantics as a concrete computation tree of trace paths. Aprograms trace-based a.i. is also a computation tree whose nodes contain abstractions ofstate and whose paths simulate the paths in the programs concrete computation tree.Using such computation trees, we provide a simple explanation of the central concept of collecting semantics, and we distinguish concrete from abstract collectingsemantics and state-based from path-based collecting semantics. We also expose therelationship between collecting semantics extraction and results garnered from flow-analytic and model-checking-based analysis techniques. We adapt concepts fromconcurrency theory to formalize safe and live a.i.s for computation trees; in particular, coinduction techniques help extend fundamental results to infinite computation trees.Problems specific to the various operational semantics methodologies are discussed: Big-step semantics cannot express divergence, so we employ a mixture of induction andcoinduction in response; small-step semantics generate sequences of programconfigurations unbounded in size, so we abstractly interpret source language syntax.Applications of trace-based a.i. to data-flow analysis, model checking, closure analysis,and concurrency theory are demonstrated.     

命令的操作语义在类型系统中的一种表示

类型系统建立在一个小的规则集合基础上，易于实现，可理解性好，且具有计算完全性和足够的表达能力,在类型系统中可以重述推导规则，将其形式化为一些归纳关系，从而直接表示了命令的操作语义,类型理论不仅适合于函数式程序的证明，也是刻画和证明命令式程序的合适的框架。     

Planning for Modular and Hybrid Fixtures

Fixturing encompasses the design and assembly of fixtures to locate and hold a workpiece during a manufacturing operation such as machining or assembly. We have implemented an automated design algorithm for a fixturing toolkit called the fixture vise; the fixture vise involves two fixture plates mounted on jaws of a vise and modular fixturing elements (pegs or flatted pegs). Generally, a fixture vise can handle appropriately sized prismatic workpieces in many different ways. The design algorithm runs in O(A) time, where A is the number of configurations achieving simultaneous contact between the modeled object and four fixture elements; since simultaneous contact is a necessary but not sufficient precondition for force closure, A provides an upper bound on the number of force closure fixture configurations. Received June 6, 1994; revised November 17, 1994, February 1, 1995, February 28, 1995, and July 11, 1995.     

Logical Semantics for the Rewriting Calculus

The Rewriting Calculus has been proposed as a language for defining term rewriting strategies. Rules are explicitly represented as terms, and are applied explicitly to other terms to transform them. Sets of rules may be applied to (sets of) terms non-deterministically to obtain sets of results. Strategies are implemented as rules which accept other rules as arguments and apply them in certain ways. This paper describes work in progress to strengthen the Rewriting Calculus by giving it a logical semantics. Such a semantics can provide crucial guidance for studying the language and increasing its expressive power. The latter is demonstrated by adding support to the Rewriting Calculus for what we call higher-form rewriting, where rules rewrite other rules. The logical semantics used is based on ordered linear logic. The paper develops the ideas through several examples.     

一种高性能大数模运算单元及其应用

为了加速公钥密码系统的实现速度,设计支持大教模乘和模加减运算的模运算单元是关键.目前的方法多关注于这两种运算的分别实现,为了改善这种方式导致的硬件单元吞吐量低的问题,提出了一种流水线结构的高性能大数模运算单元.基于改进的Montgomery模乘算法,采用流水线技术,把模乘电路分成3个流水线阶段,并把模加减电路结合到第3阶段,得到一种能同时计算模乘和模加减的模运算单元.仿真结果显示,模运算单元以较少的资源占用率获得了较高的吞吐量,非常适合做高性能的公钥密码系统的基本硬件运算单元.     

Modular supervisory control of discrete-event systems

A modular approach to the supervisory control of a class of discrete-event systems is formulated, and illustrated with an example. Discrete-event systems are modeled by automata together with a mechanism for enabling and disabling a subset of state transitions. The basic problem of interest is to ensure by appropriate supervision that the closed loop behavior of the system lies within a given legal behavior. Assuming this behavior can be decomposed into an intersection of component restrictions, we determine conditions under which it is possible to synthesize the appropriate control in a modular fashion. The work of this author was supported by NSERC (Canada) under Grant No. A-7399. The work of this author was supported by the National Science Foundation through Grant No. ECS-8504584.     

开放型模块式结构单片机实验箱设计

当前单片机实验教学设备存在实验内容简单、程序固定的弊端,学生自主操作的空间很小,与工程实际相差甚远。针对这一问题提出改进设计方案,从工程开发的角度设计各功能模块,基于开放式设计理念,各功能模块与母板采用可拆卸式的连接,方便组成不同实验的硬件电路,具有很强的可扩展性。既可以完成基本的实验教学需要,又增加了灵活操作的空间,学生可以自主进行系统硬件和软件的设计,切实锻炼了学生的实践技能,培养了学生的工程意识。目前,该实验箱已经在两所院校推广应用。     

An Operational Semantics for Shared Messaging Communication

Shared Messaging Communication (SMC) has been introduced in [Satya Kiran M.N.V., Jayram M.N., Pradeep Rao, and S.K. Nandy. A complexity effective communication model for behavioral modeling of signal processing applications. In Proceedings of 40th Design Automation Conference, 2003] as a model of communication which reduces communication costs (both in terms of communication latency and memory usage) by allowing tasks to communicate data through special shared memory regions. Sending a reference to an otherwise inaccessible memory regions rather than the data itself, the model combines the advantages of message passing and shared memories. Experimental results have shown that SMC in case of large data payloads clearly outperforms the classical message passing.In this paper we give a formal operational semantics to SMC exhibiting unambiguously the effect of executing an SMC command on local and shared memories. Based on this semantics we show that any program using message passing can be proved to be weakly bisimilar to one based on SMC and that with respect to communication costs the latter is amortised cheaper, [A. Kiehn and S. Arun-Kumar. Amortised bisimulations. In Proceedings of FORTE 2005, number 3731 in Lecture Notes in Computer Science, pages 320–334. Springer-Verlag, 2005].     

An Unboxed Operational Semantics for ML Polymorphism

We present an unboxed operational semantics for an ML-style polymorphic language. Different from the conventional formalisms, the proposed semantics accounts for actual representations of run-time objects of various types, and supports a refined notion of polymorphism that allows polymorphic functions to be applied directly to values of various different representations. In particular, polymorphic functions can receive multi-word constants such as floating-point numbers without requiring them to be boxed (i.e., heap allocated.) This semantics will serve as an alternative basis for implementing polymorphic languages. The development of the semantics is based on the technique of the type-inference-based compilation for polymorphic record operations [20]. We first develop a lower-level calculus, called a polymorphic unboxed calculus, that accounts for direct manipulation of unboxed values in a polymorphic language. This unboxed calculus supports efficient value binding through integer representation of variables. Different from de Bruijn indexes, our integer representation of a variable corresponds to the actual offset to the value in a run-time environment consisting of objects of various sizes. Polymorphism is supported through an abstraction mechanism over argument sizes. We then develop an algorithm that translates ML into the polymorphic unboxed calculus by using type information obtained through type inference. At the time of polymorphic let binding, the necessary size abstractions are inserted so that a polymorphic function is translated into a function that is polymorphic not only in the type of the argument but also in its size. The ML type system is shown to be sound with respect to the operational semantics realized by the translation.