Teaching Java backwards

Teaching programming concepts in a more object-oriented way is a growing trend in Computer Science education. This paper takes the idea of abstraction-first teaching a step further, by using Bloom’s Taxonomy to design a course to present factual content early, followed by higher-level cognitive skills. In the course described here, factual content was covered rapidly, then reinforced by assignments, laboratory sessions and tutorials, aimed at building higher cognitive skills. The resulting course was successful in relatively rapidly bringing a class doing a “bridging” diploma up to the level required for dealing with a second-year course. As compared with previous runs of the diploma where much more time was spent in preparation for advanced courses, the class using the new approach performed better, suggesting that the approach used is worthy of further study.     

A new algorithm for testing if a regular language is locally threshold testable

A new algorithm is presented for testing if a regular language is locally threshold testable. The new algorithm is slower than existing algorithms, but its correctness proof is shorter. The proof idea is to restate the problem in Presburger arithmetic.     

High-level distributed coordination via distributed Haskell

With the boom of Networks and Internet, more and more applications have an inherent distributed character. Distributed functional language can support high-level distributed coordination with automatic management of many coordination aspects, due to its features like good abstraction mechanisms, a high-level computation language, and sophisticated type system. This paper briefly reviews the features and benefits of functional language Glasgow distributed Haskell （GdH）. It also compares GdH with object-oriented distributed languages. It concludes that GdH potentially offers significant benefits for constructing high-level distributed coordination.     

Systematic pattern selection using pattern language grammars and design space analysis

Software patterns provide reusable solutions to recurring design problems in a particular context. The software architect or designer must find the relevant patterns and pattern languages that need to be considered, and select the appropriate patterns, as well as the best order to apply them. If the patterns and pattern languages are written by multiple pattern authors, it might be necessary to identify interdependencies and overlaps between these patterns and pattern languages first. Out of the possible multitude of patterns and pattern combinations that might provide a solution to a particular design problem, one fitting solution must be selected. This can only be mastered with a sufficient expertise for both the relevant patterns and the domain in which they are applied. To remedy these issues we provide an approach to support the selection of patterns based on desired quality attributes and systematic design decisions based on patterns. We propose to formalize the pattern relationships in a pattern language grammar and to annotate the grammar with effects on quality goals. In a second step, complex design decisions are analyzed further using the design spaces covered by a set of related software patterns. This approach helps to systematically find and categorize the appropriate software patterns—possibly even from different sources. As a case study of our approach, we analyze patterns from a pattern language for distributed object middleware. Copyright © 2006 John Wiley & Sons, Ltd.     

CrimeSPOT: A language and runtime for developing active wireless sensor network applications

Advances in wireless sensing and actuation technology allow embedding significant amounts of application logic inside wireless sensor networks. Such active WSN applications are more autonomous, but are significantly more complex to implement. Event-based middleware lends itself to implementing these applications. It offers developers fine-grained control over how an individual node interacts with the other nodes of the network. However, this control comes at the cost of event handlers which lack composability and violate software engineering principles such as separation of concerns. In this paper, we present CrimeSPOT as a domain-specific language for programming WSN applications on top of event-driven middleware. Its node-centric features enable programming a node’s interactions through declarative rules rather than event handlers. Its network-centric features support reusing code within and among WSN applications. Unique to CrimeSPOT is its support for associating application-specific semantics with events that carry sensor readings. These preclude transposing existing approaches that address the shortcomings of event-based middleware to the domain of wireless sensor networks. We provide a comprehensive overview of the language and the implementation of its accompanying runtime. The latter comprises several extensions to the Rete forward chaining algorithm. We evaluate the expressiveness of the language and the overhead of its runtime using small, but representative active WSN applications.     

Local multi-valued logics in modular expert systems

Abstract

Abstract. In this paper we describe an approach to the problem of dealing with uncertainty by means of finite multi-valued logics in modular expert systems, and the results obtained. The modularity of the systems allows us to address two main characteristics of human problem-solving: the adaptation of general knowledge to particular problems and the dependency of the management of uncertainty on the different subtasks being implemented in the modules of the system, i.e. different modules can have different local multiple-valued logics as part of their local deductive mechanisms. Although the results obtained are general, we use, throughout the paper, examples of a medical expert system that has been designed using a modular language called MILORD-II, that implements them showing the practical interest of the theoretical concepts involved.     

Teams in cooperating grammar systems

Abstract

We consider grammar systems in which several components are active at the same moment (a team of components is working). The power of such mechanisms is investigated and it is found that in many cases the team feature increases the generative capacity of grammar systems. In the so-called t-mode of derivation (a team works as much as it can) it is found that the team size does not induce an infinite hierarchy of languages. However, the family obtained in this case is a full abstract family of languages properly including ETOL.     

GLL parse-tree generation

Backtracking techniques which are often used to extend recursive descent (RD) parsers can have explosive run-times and cannot deal with grammars with left recursion. GLL parsers are fully general, worst-case cubic parsers which have the recursive descent-like property that they are easy to write and to use for grammar debugging. They have the direct relationship with the grammar that an RD parser has. In this paper we give an algorithm for generating GLL parsers which build an SPPF representation of the derivations of the input, complementing our existing GLL recognition algorithm, and we show that such parsers and recognisers are worst-case cubic.     

Quad‐Mesh Generation and Processing: A Survey

Triangle meshes have been nearly ubiquitous in computer graphics, and a large body of data structures and geometry processing algorithms based on them has been developed in the literature. At the same time, quadrilateral meshes, especially semi‐regular ones, have advantages for many applications, and significant progress was made in quadrilateral mesh generation and processing during the last several years. In this survey we discuss the advantages and problems of techniques operating on quadrilateral meshes, including surface analysis and mesh quality, simplification, adaptive refinement, alignment with features, parametrisation and remeshing.