算法程序变换研究与进展

开发算法程序是计算机科学领域中最具挑战性的问题之一。为了提高算法程序的可靠性和生产效率,人们正在追求其开发的自动化。算法程序变换是实现算法程序开发自动化的重要途径,已成为程序设计方法学和软件自动化领域中的重要课题,目前已取得很大进展。本文介绍了算法程序变换的相关概念,给出了算法程序变换的分类,并从方法学、语言、算法设计能力、支撑工具及其适用领域等方面分析和比较了几个有代表性的算法程序变换研究项目,讨论了当前研究的不足以及今后的研究方向。     

Formal verification of a modern SAT solver by shallow embedding into Isabelle/HOL

We present a formalization and a formal total correctness proof of a MiniSAT-like SAT solver within the system Isabelle/HOL. The solver is based on the DPLL procedure and employs most state-of-the-art SAT solving techniques, including the conflict-guided backjumping, clause learning, and the two-watched unit propagation scheme. A shallow embedding into Isabelle/HOL is used and the solver is expressed as a set of recursive HOL functions. Based on this specification, the Isabelle’s built-in code generator can be used to generate executable code in several supported functional languages (Haskell, SML, and OCaml). The SAT solver implemented in this way is, to our knowledge, the first fully formally and mechanically verified modern SAT solver.     

The formalism underlying EASYMAP: A precompiler for refinement-based exploration of hierarchical data organizations

In the computer science community, data structure design is mainly conducted at a high level of abstraction under the implicit assumption that the platform contains a monolithic memory. Exploiting platform-related knowledge such as available on-chip and off-chip memory sizes, the cache size, and the number of banks is mainly conducted in the system engineering community when the refined data structure has already been chosen. A convergence of both communities is desirable since this can lead to powerful optimizations.To achieve the convergence mentioned above, data-related transformations have been researched extensively in the recent past. Many of these transformations have a direct and large impact on memory footprint, execution time and energy consumption. Unfortunately, however, the most effective transformations are applied manually (e.g. in C code) and these result in a very time-consuming and error-prone design process. To overcome this burden, our general research goal is to develop a computer-aided design tool, called , that helps the designer to correctly construct the C code of an efficient but difficult-to-understand data structure. The formal design of is the topic of this article with the emphasis on , the internal language of . is based on a novel extension of Separation Logic’s spatial conjunction operator (∗), allowing it to concisely describe access operations of an irregularly accessed complex data organization. is the basic building block of ; it serves the purpose of automating ’s refinement process and proving that it is correct by construction.     

An ontological approach for reliable data integration in the industrial domain

Ontologies are structural components of modern information systems. The taxonomy, the core of an ontology, is a delicate balance between adequacy considerations, minimal commitments and implementation concerns. However, ontological taxonomies can be quite restrictive and entities that are commonly used in production and services might not find room in a official or de facto standard or ontological system. This mismatch between the company's view and the ontological constraints can limit or even jeoparize the adoption of modern formal ontologies in industry. We study the roots of this problem and individuate a general set of principles to relate the ontology and those non-ontological entities that are yet important for the core business of the company. We then introduce a theoretically sound and formally robust approach to expand a given ontology with new dependency relations, which make available information regarding the non-ontological entities without affecting the consistency of the overall information system.     

一种时态数据形式语言模型

数据模型是数据库技术发展的主线,时态数据模型是时态数据库系统的核心与基础。针对时态数据模型的研究现状,初步探讨了时态数据模型的基本要素,建立了一种形式化时态数据模型;基于形式语言理论和形式语义学的指称语义方法,进一步建立了该时态数据模型的形式语言模型。应用时态数据形式语言模型定义了各类时态完整性约束的形式语义规则,深入分析了时态数据模型内在的时态语义联系,为时态数据模型的研究提供了一个便利、高效的形式化理论框架。     

支持抽象解释的静态分析方法的形式化体系研究

在安全关键领域中,如何保证软件的安全性已经成为了一个广受关注的重要课题。静态程序分析是一类十分有效的程序自动化验证方法。基于抽象解释的静态分析技术在验证软件的非功能性安全属性上表现十分突出。可配置程序分析(Configurable Program Analysis,CPA)是一种通用静态分析方法形式化体系,旨在用一种形式化体系对静态分析的分析阶段进行建模。使用CPA对基于抽象解释的静态分析进行建模,给出如何使用CPA形式化体系描述基于抽象解释的静态分析,给出了从待分析程序到CPA形式化体系的转换规则;提供了一种在安全关键性领域中的软件正确性自动验证方法,为基于抽象解释的静态分析工具的实现提供了一种可行方案。     

Essential concepts of algebraic specification and program development

The main ideas underlying work on the model-theoretic foundations of algebraic specification and formal program development are presented in an informal way. An attempt is made to offer an overall view, rather than new results, and to focus on the basic motivation behind the technicalities presented elsewhere.     

The Chu construction and generalized formal concept analysis

We continue studying the connections between the Chu construction on the category ChuCors of formal contexts and Chu correspondences, and generalizations of Formal Concept Analysis (FCA). All the required constructions like categorical product, tensor product, together with its bifunctor properties are introduced and proved. The final section focuses on how the second-order generalization of FCA can be built up in terms of the Chu construction.