P Systems with Mobile Membranes

P systems with active membranes are among the central ones in membrane computing, and they were shown to be both computationally universal (able to simulate Turing machines) and computationally efficient (able to solve hard problems in polynomial time). However, in all cases, these results were obtained by making use of several powerful features, such as membrane polarization, label changing, division of non-elementary membranes, priorities, or cooperative rules. This paper contributes to the research effort of introducing a class of P systems with active membranes having none of the features mentioned above, but still preserving the power and the efficiency. The additional feature we consider instead are the operations of endocytosis and exocytosis: moving a membrane inside a neighboring membrane, or outside the membrane where it is placed. We investigate the power and the efficiency of these systems (also using membrane division) by first proving that they can simulate (with a linear slowdown and without introducing non-determinism) rewriting P systems with 2-replication, for which the universality and the possibility of solving NP-complete problems in polynomial time are known. In this way, the universality and efficiency are also obtained for our systems. We also give a direct and simple proof for the universality result – without using division rules (the proof uses nine membranes, but we do not know whether this number can be decreased).     

SATHE: Some aspects of an ALGOL implementation

The development of a compiler for a dialect of ALGOL 60 is described. The emphasis is on the strategies used in the detection and smooth recovery from errors in the input text. These strategies are independent of both the language implemented and the implementation language. The user's view is such that he sees an ALGOL machine: the user is addressed in a language he is familiar with, using notions from the programming language and his particular program only.     

Design and implementation of an adaptable software environment

In any major software project, a large volume of project-related information must be maintained and manipulated throughout the software life-cycle. Often this information is scattered, in different media ranging from scraps of papers to program listings, poorly cross-referenced, and inaccessible. TRIAD, an adaptable, integrated software development environment, has been designed to integrate and manage all this information in an organized and structured manner.

The TRIAD tool-box environment supports different methodologies to guide the users during development and maintenance of project related information. The environment can be customized by selecting a set of forms which enforce a particular methodology. These forms help develop, integrate, and maintain project information. Forms for a methodology can be tuned to reflect a project-team's experience. When customized by the tuned methodology, TRIAD can provide better project oriented support.

TRIAD uses grammar forms as its organizational model. This paper will discuss the advantages of using grammar forms in the modeling and implementation of an adaptable software information editor, within the TRIAD tool-box environment.     

C语言switch语句的一种文法改写方法

为了使C语言中的switch语句被计算机理解,首先要对其建立文法并对其进行文法改写。针对switch语句,提出一种文法改写方法。该方法采用自底向上的语法制导翻译方法,根据switch语句代码结构的特点,利用拆分法,使得改写前后的文法完全等价,只要给出语义动作,就能实现switch语句的翻译。这种方法不会对原文法的语法分析带来影响,而且使得分析程序在栈中存取语义信息更方便。     

Grammar engineering for multiple front-ends for Python

In this paper, we describe our experience in grammar engineering to construct multiple parsers and front ends for the Python language. We present a metrics-based study of the evolution of the Python grammars through the multiple versions of the language in an effort to distinguish and measure grammar evolution and to provide a basis of comparison with related research in grammar engineering. To conduct this research, we have built a toolkit, pygrat , which builds on tools developed in other research. We use pygrat to build a system that automates much of the process needed to translate the Python grammars from EBNF to a formalism acceptable to the bison parser generator. We exploit the suite of Python test cases, used by the Python developers, to validate our parser generation. Finally, we describe our use of the menhir parser generator to facilitate the parser and front-end construction, eliminating some of the transformations and providing practical support for grammar modularisation.     

形状文法在传统纹样演化设计中的应用研究

目的提出一种适用于传统纹样的演化设计方法,使设计对象更好地继承优秀特质并满足时代的审美需求。方法通过分析传统纹样的典型特征,提取核心图元作为初始形状,结合流行元素,利用形状文法生成新的纹样设计方案。结论基于形状文法的传统纹样再设计创新方法,既保证了新纹样的创新性,又保留了传统纹样的代表性特征,为现代纺织业以传统文化为设计创新源泉进行转型升级提供了一种可能的方向,并通过某款新疆和田手工编织毯的纹样设计验证了可行性。     

基于立春节气的文创产品设计方法

目的提取立春节气文化中蕴含的特色设计因子,丰富节气文创产品种类,满足用户多样化需求,保持和发展文化特色。方法采用文献阅读和综述等方法收集立春节气资料,通过问卷调研的形式发现有效信息;创建基于立春节气设计因子的提取模型,使用思维导图筛选显著特征;针对立春节气文创产品设计,从隐性因子和显性因子出发,对立春节气的设计因子进行可视化处理;将生成的立春节气纹样根据形状文法的不同推演规则,推演出更多立春节气新纹样和新图形。结论立春节气丝巾的纹饰创新设计验证了该提取模型的可行性和合理性,拓宽了文创产品的设计思路,提高了设计对象的文化内涵,促进了传统文化的传承和发展。     

一种基于属性文法的C 静态语义描述

主要讨论了利用属性文法对Ｃ＋＋中在类的定义、对象说明、成员函数、继承与派生等方面涉及的全局及局部静态性质进行形式化描述的方法。     

A Bi‐Directional Procedural Model for Architectural Design

It is a challenge for shape grammars to incorporate spatial hierarchy and interior connectivity of buildings in early design stages. To resolve this difficulty, we developed a bi‐directional procedural model: the forward process constructs the derivation tree with production rules, while the backward process realizes the tree with shapes in a stepwise manner (from leaves to the root). Each inverse‐derivation step involves essential geometric‐topological reasoning. With this bi‐directional framework, design constraints and objectives are encoded in the grammar‐shape translation. We conducted two applications. The first employs geometric primitives as terminals and the other uses previous designs as terminals. Both approaches lead to consistent interior connectivity and a rich spatial hierarchy. The results imply that bespoke geometric‐topological processing helps shape grammar to create plausible, novel compositions. Our model is more productive than hand‐coded shape grammars, while it is less computation‐intensive than evolutionary treatment of shape grammars.