Coupled Transformation of Schemas, Documents, Queries, and Constraints

Coupled transformation occurs when multiple software artifacts must be transformed in such a way that they remain consistent with each other. For instance, when a database schema is adapted in the context of system maintenance, the persistent data residing in the system's database needs to be migrated to conform to the adapted schema. Also, queries embedded in the application code and any declared referential constraints must be adapted to take the schema changes into account. As another example, in XML-to-relational data mapping, a hierarchical XML Schema is mapped to a relational SQL schema with appropriate referential constraints, and the XML documents and queries are converted into relational data and relational queries. The 2LT project is aimed at providing a formal basis for coupled transformation. This formal basis is found in data refinement theory, point-free program calculation, and strategic term rewriting. We formalize the coupled transformation of a data type by an algebra of information-preserving data refinement steps, each witnessed by appropriate data conversion functions. Refinement steps are modeled by so-called two-level rewrite rules on type expressions that synthesize conversion functions between redex and reduct while rewriting. Strategy combinators are used to composed two-level rewrite rules into complete rewrite systems. Point-free program calculation is applied to optimized synthesize conversion function, to migrate queries, and to normalize data type constraints. In this paper, we provide an overview of the challenges met by the 2LT project and we give a sketch of the solutions offered.     

Term-graph Rewriting in Tom Using Relative Positions

In this paper, we present the implementation in Tom of a de Bruijn indices generalization allowing the representation of term-graphs over an algebraic signature. By adding pattern matching and traversal controls to Java, Tom is a well-suited environment for defining program transformations or analyses. As some analyses, e.g. based on control flow, require graph-like structures, the use of this formalism is a natural way of expressing them by graph rewriting.     

A Rewriting Machine and Optimization of Strategies of Term Rewriting

An algebraic specification of a new rewriting machine for fast rewriting of terms is considered. Theorems on the correctness of this specification are proved. A method for optimization of a strategy of iterative rewriting is proposed.     

Strategy Construction in the Higher-Order Framework of TL

When viewed from a strategic perspective, a labeled rule base in a rewriting system can be seen as a restricted form of strategic expression (e.g., a collection of rules strictly composed using the left-biased choice combinator). This paper describes higher-order mechanisms capable of dynamically constructing strategic expressions that are similar to rule bases. One notable difference between these strategic expressions and rule bases is that strategic expressions can be constructed using arbitrary binary combinators (e.g., left-biased choice, right-biased choice, sequential composition, or user defined). Furthermore, the data used in these strategic expressions can be obtained through term traversals.A higher-order strategic programming framework called TL is described. In TL it is possible to dynamically construct strategic expression of the kind mentioned in the previous paragraph. A demonstration follows showing how the higher-order constructs available in TL can be used to solve several problems common to the area of program transformation.     

模型转换的重写逻辑构架研究

规则式的模型转换技术在模型驱动构架的模型转换实施中占有重要地位,但目前诸实施对于转换规则的定义存在多种解释、转换的协调方面、终止性和一致性等数学属性缺乏支持。该文提出一种Maude重写逻辑基础的构架(RLBA)以实施模型转换,通过产生式规范、多方法风格的重写规则集设计、OC(对象配置)和OM(对象消息)重写规则分类等技术并结合模型检查工具,为自动产生元模型和模型的面向对象可执行代数规范、转换规则的严格形式化定义、转换协调方面的刻画、终止性和一致性等的验证提供支持。     

基于重写技术的程序开发与验证

完整地介绍了一个基于重写技术的程序开发和验证系统,重点展示验证子系统的理论、方法 和技术.验证子系统使得系统能自动证明程序和规范中的优化规则及测试等式,从而进一步保 证程序开发过程的正确性.验证子系统所采用的主要技术是以成批证明方法和证据测试集为 特色的重写归纳方法.     

From Chemical Rules to Term Rewriting

In this paper, rule-based programming is explored in the field of automated generation of chemical reaction mechanisms. We explore a class of graphs and a graph rewriting relation where vertices are preserved and only edges are changed. We show how to represent cyclic labeled graphs by decorated labeled trees or forests, then how to transform trees into terms. A graph rewriting relation is defined, then simulated by a tree rewriting relation, which can be in turn simulated by a rewriting relation on equivalence classes of terms. As a consequence, this kind of graph rewriting can be implemented using term rewriting. This study is motivated by the design of the GasEl system for the generation of kinetics reactions mechanisms. In GasEl, chemical reactions correspond to graph rewrite rules and are implemented by conditional rewriting rules in ELAN. The control of their application is done through the ELAN strategy language.     

C-Java自动程序转换系统的设计

程序设计语言的相互转换技术可以被广泛运用在软件维护、遗留系统的升级改造以及软件逆向工程等领域中。文中先对现有的几种移植方法进行了分析和研究,分析表明在将程序库移植到Java中和将它们与Java整合时,这些方法暴露出了各自的局限性和不足。借鉴语言转换经验,制定了转换的设计原则并探讨了将C语言转换到Java语言的过程中需要解决的一些问题,以及这个转换系统的设计思想和实现方法。文中所阐述的内容为实现异种程序设计语言的程序代码转换,提高程序代码的可移植性和重用性提供了有意义的思路和实现方法。     

几种递归变换的改进模式

递归变换是程序自动设计中的一个研究课题。文[3,4]分别提出了几种递归变换,其可用条件中都包括单位元.我们基于文[8]的思想,讨论了对文[3,4]中几种变换的改进。