Deterministic finite automata with recursive calls and DPDAs

We study deterministic finite automata (DFA) with recursive calls, that is, finite sequences of component DFAs that can call each other recursively. DFAs with recursive calls are akin to recursive state machines and unrestricted hierarchic state machines. We show that they are language equivalent to deterministic pushdown automata (DPDA).     

浅析波普艺术中的装饰语言

从人类运用艺术来表达感情和生活始,装饰与艺术便如影随形。波普艺术作为重要的艺术流派,其中的装饰语言值得人们探究。本文以波普艺术为切入点,重点从装饰图案的角度解析波普艺术中的装饰语言。结合产生的背景,分析波普艺术采用装饰图案的产生原因;再以色彩、形式等方面分析波普风格装饰图案的特征,寻求波普艺术视觉审美中的亮点,以期能对中国当代设计艺术有所启发与帮助。     

Real-Time GPU Silhouette Refinement using Adaptively Blended Bézier Patches

We present an algorithm for detecting and extracting the silhouette edges of a triangle mesh in real time using Graphical Processing Units (GPUs). We also propose a tessellation strategy for visualizing the mesh with smooth silhouettes through a continuous blend between Bézier patches with varying level of detail. Furthermore, we show how our techniques can be integrated with displacement and normal mapping. We give details on our GPU implementation and provide a performance analysis with respect to mesh size.     

Object query optimization through detecting independent subqueries

The problem of query optimization in object-oriented databases is addressed. We follow the Stack-Based Approach to query languages, which employs the naming-scoping-binding paradigm of programming languages rather than traditional database concepts such as relational/object algebras or calculi. The classical environment stack is a semantic basis for definitions of object query operators, such as selection, projection/navigation, dependent join, and quantifiers. We describe a general object data model and define a formalized OQL-like query language SBQL. Optimization by rewriting concerns queries containing so-called independent subqueries. It consists in detecting them and then factoring outside loops implied by query operators. The idea is based on the formal static analysis of scoping rules and binding names occurring in a query. It is more general than the classical pushing selections/projections before joins.     

CIRL/PIWI: A GUI toolkit supporting retargetability

Writing applications that are easily moved to various computer platforms with different graphical user interfaces (GUIs) is a complex task. Yet this concept is important for the creator of commercial software, as it is not likely to be clear for many years whether one or two GUIs will survive and become industry ‘standards’ or whether the growth in GUIs will continue because of new developments in human-computer interfaces. Providing a user interface abstraction that maps into all toolkits seems to be an appropriate way to proceed, but is fraught with difficulty. For example, different GUIs present a different look-and-feel that often causes system-specific information to be embedded in an application. This paper surveys the problems inherent in designing a user interface abstraction, and describes the experiences gained from a specific implementation called CIRL/PIWI.

1 CIRL and PIWI are acronyms for Co-ordinate-Independent Resource Language and Presentation-Independent Windowed Interface.

The user interface abstraction contains a knowledge base that allows many components of the user interface to be defined independent of look-and-feel thereby increasing the portability of an application.     

GPU Shape Grammars

GPU Shape Grammars provide a solution for interactive procedural generation, tuning and visualization of massive environment elements for both video games and production rendering. Our technique generates detailed models without explicit geometry storage. To this end we reformulate the grammar expansion for generation of detailed models at the tesselation control and geometry shader stages. Using the geometry generation capabilities of modern graphics hardware, our technique generated massive, highly detailed models. GPU Shape Grammars integrate within a scalable framework by introducing automatic generation of levels of detail at reduced cost. We apply our solution for interactive generation and rendering of scenes containing thousands of buildings and trees.     

汉语国际教育本科专业中华才艺课程体系研究

中华才艺课程在海外汉语教学中占据着十分重要的地位,针对国内汉语国际教育本科专业中华才艺课程存在课程目标不明确、课程性质定位与实际需求不符合、课程内容不确定、课程考核方式不科学的现状,试图从中华才艺培养的可展示性、实践性和持续性等角度出发,建立一个科学有效可操作性强的中华才艺课程体系,并提出了与之相关的考评模式、实验室建设模式。     

On Pattern Frequency Occurrences in a Markovian Sequence

Consider a given pattern H and a random text T generated by a Markovian source. We study the frequency of pattern occurrences in a random text when overlapping copies of the pattern are counted separately. We present exact and asymptotic formulae for moments (including the variance), and probability of r pattern occurrences for three different regions of r , namely: (i) r=O(1) , (ii) central limit regime, and (iii) large deviations regime. In order to derive these results, we first construct certain language expressions that characterize pattern occurrences which are later translated into generating functions. We then use analytical methods to extract asymptotic behaviors of the pattern frequency from the generating functions. These findings are of particular interest to molecular biology problems (e.g., finding patterns with unexpectedly high or low frequencies, and gene recognition), information theory (e.g., second-order properties of the relative frequency), and pattern matching algorithms (e.g., q -gram algorithms).