Performance evaluation methodologies for abstract data type implementation techniques

The runtime management system for a programming language must allow the efficient manipulation of complex objects, such as instances of abstract data types (ADTs). We describe an implementation model for ADTs based on coroutine objects (i.e. as an alternative to ad hoc modifications of the runtime stack). We evaluate the performances of variants of our implementation model using two different approaches: a benchmarking technique which monitors actual costs for test programs and a “pseudo-execution” technique which estimates costs based on idealized instruction timings. The results of our comparison indicate that the two forms of evaluation give very similar cost estimates, supporting the use of the (cheaper) pseudo-execution technique. The overall performance results identify applications in which our coroutine implementation model has definite strengths and weaknesses. Finally, our implementation approach is compared with modified stack implementations used in other ADT systems.     

Replicated abstract data types: Building blocks for collaborative applications

For distributed applications requiring collaboration, responsive and transparent interactivity is highly desired. Though such interactivity can be achieved with optimistic replication, maintaining replica consistency is difficult. To support efficient implementations of collaborative applications, this paper extends a few representative abstract data types (ADTs), such as arrays, hash tables, and growable arrays (or linked lists), into replicated abstract data types (RADTs). In RADTs, a shared ADT is replicated and modified with optimistic operations. Operation commutativity and precedence transitivity are two principles enabling RADTs to maintain consistency despite different execution orders. Especially, replicated growable arrays (RGAs) support insertion/deletion/update operations. Over previous approaches to the optimistic insertion and deletion, RGAs show significant improvement in performance, scalability, and reliability.     

移动空间数据类型和操作的初步研究

1 引言移动空间对象是随时间变化的空间数据,由时空数据库(Spatio-Temporal Databases)进行管理和处理。一个空间点可能随时间而改变其位置,为了完整地反映该点的信息,数据库中应该存储该点的全部历史信息,这个空间对象就是一个移动点。同理,一个区域也可能随时间移动、扩大或缩小。时空现象在现实生活中非常普遍,如飞机航行时随着时间变化而改变它的空间位置,这飞机就是一个移动点;当森林中某处发生火灾时,火灾区就是一个空间对象:区域。该区域可能     

智能化图象数据库系统的GBASE的模式设计

知识化图象数据库系统近年来引起了人们的研究兴趣,表现出了广泛的应用前景.本文 介绍一种知识化图象数据库管理系统GBASE的模式设计,它将传统的关系模式加以扩充,使 之能容许框架知识表达的抽象数据类型(ADTs),增强了关系数据库系统的语义描述能力,有 助于表达有关图象实体以及它们之间的空间关系等有关知识.利用ADT我们可以进行知识 引导下的数据库查询、图象实体空间关系的推理以及基于应用模型的辅助设计和规划.GBASE 系统是在VAX11/750机上在VMS操作系统下,以C语言完成的.它统一管理着多种类型 的信息,即关系数据、图形、图象数据、知识以及过程等,是一个综合的图象数据库管理系统. 目前正应用于林业资源的管理和规划.     

对象技术与抽象数据类型的实现

讨论了抽象数据类型的实现方案，并以“线性表”为例，说明对象技术在抽象数据类型实现中的应用。对于一种抽象的数据类型，先将它定义成一个抽象类，再结合某一种具体的存储方式加以实现。采用这种对象技术的特点是，任何存储方式或实现细节的改变都不会影响外界对类的使用。这种设计原则已应用于面向对象版的“数据结构”课程之中，取得了良好的效果。     

A relational realizability model for higher-order stateful ADTs

We present a realizability model for reasoning about contextual equivalence of higher-order programs with impredicative polymorphism, recursive types, and higher-order mutable state.The model combines the virtues of two recent earlier models: (1) Ahmed, Dreyer, and Rossberg’s step-indexed logical relations model, which was designed to facilitate proofs of representation independence for “state-dependent” ADTs and (2) Birkedal, Støvring, and Thamsborg’s realizability logical relations model, which was designed to facilitate abstract proofs without tedious step-index arithmetic. The resulting model can be used to give abstract proofs of representation independence for “state-dependent” ADTs.     

Polymorphic type-checking in scheme

This paper presents a type-inference system for Scheme that is designed to be used by students in an introductory programming course. The major goal of the work is to present a type system that is simple enough to be used by beginner students, yet is powerful enough to express the ideas of polymorphism, abstract data types (ADTs), and higher-order procedures. The system also performs some rudimentary syntax checking. The system uses subtyping, but only in a primitive fashion. It has a type datum which is a supertype of all types, and a type poof which is a subtype of all types. It uses intersection types to control the use of datum and to generate simple but accurate types.     

On the practical need for abstraction relations to verify abstractdata type representations

The typical correspondence between a concrete representation and an abstract conceptual value of an abstract data type (ADT) variable (object) is a many-to-one function. For example, many different pointer aggregates give rise to exactly the same binary tree. The theoretical possibility that this correspondence generally should be relational has long been recognized. By using a nontrivial ADT for handling an optimization problem, the authors show why the need for generalizing from functions to relations arises naturally in practice. Making this generalization is among the steps essential for enhancing the practical applicability of formal reasoning methods to industrial-strength software systems     

Modelling form-based interfaces with bipartite state machines

This article presents the concept of form storyboarding, a new modelling method for eliciting, specifying and communicating functional requirements of applications with form-based interfaces. We identify two-staged interaction as the abstract concept behind form-based interfaces. The method encompasses a visual language for the documents to be created and a set of proposals for the activities involved in that. The method fits to different and ubiquitous types of submit/response style interfaces, i.e. mainframe terminals as well as web-based interfaces. The method yields an abstract interface model based on bipartite state machines. The model is executable and can be used for automatic prototype generation. Form storyboarding is first and foremost a feature-driven approach. The whole form storyboard can be obtained by collecting single system features. Crucial for this approach is the fact that diagrams can be combined in an easy operation, by building the union of both diagrams and identifying nodes and edges with the same name.     

Application of a neural network to a design optimization process

This article discusses the implementation of a class of design problems in a neural network. the problems, identified at an abstract (i.e., connectivity) level of building design, are characterized as optimization types of problems. Architects often have to generate floor-plan layouts of a building optimized with respect to several points of view. Examples of these points of view, often stated in terms of normative requirements, are the social norms: community, privacy, and circulation-cost. an architectural design problem in the presence of even a single norm from among the above norms is computationally hard and intractable. During the last four decades there have been attempts to automate floor-plan design considering a single norm or a limited number norms. Most of these attempts have traditionally been based on combinatorial enumeration methods. Recent progress in AI has paved the way for intelligent handling of the architectural design processes using knowledge-based system technology and heuristics programming. This article examines the possibility of the neural networks approach in generating connectivity patterns of building with respect to specific social norms. Our first attempt has been focused on linear-tree type designs with respect to single norms. the idea in this work was borrowed from the Hopfield model of the neural network for implementation of the Traveling Salesman Problem, because of the similarity of our design problems with this problem. Hopfield and other researchers used constant parameters for different-sized problems. Close examination of the network and experiments revealed that this approach does not guarantee a convergence for every case, and chaotic behavior is expected in cases for which the chosen parameters are not appropriate. to overcome this problem this article suggests problem-dependent and problem-size-dependent parameters that vary for each case. Test results from the implementation convey that the approach yields satisfactory results and is worth it to explore its application to other classes of optimization problems.     

Tool-assisted unit-test generation and selection based on operational abstractions

Unit testing, a common step in software development, presents a challenge. When produced manually, unit test suites are often insufficient to identify defects. The main alternative is to use one of a variety of automatic unit-test generation tools: these are able to produce and execute a large number of test inputs that extensively exercise the unit under test. However, without a priori specifications, programmers need to manually verify the outputs of these test executions, which is generally impractical. To reduce this cost, unit-test selection techniques may be used to help select a subset of automatically generated test inputs. Then programmers can verify their outputs, equip them with test oracles, and put them into the existing test suite. In this paper, we present the operational violation approach for unit-test generation and selection, a black-box approach without requiring a priori specifications. The approach dynamically generates operational abstractions from executions of the existing unit test suite. These operational abstractions guide test generation tools to generate tests to violate them. The approach selects those generated tests violating operational abstractions for inspection. These selected tests exercise some new behavior that has not been exercised by the existing tests. We implemented this approach by integrating the use of Daikon (a dynamic invariant detection tool) and Parasoft Jtest (a commercial Java unit testing tool), and conducted several experiments to assess the approach. This article is an invited submission to the Automated Software Engineering Journal. An earlier version of this article appeared in Proceedings of the 16th IEEE Conference on Automated Software Engineering (ASE 2003).     

Chasing real-time interaction in new media: towards a new theoretical approach and definition

‘Real-Time’ is one of the most frequent concepts used referring to digital media. Despite it is commonly related to immediate feedback, it is not clear when it happens and what its characteristics are, especially in current digital interfaces. Although real-time has been written about very extensively in the context of Human Computer Interaction and Computational Systems, there are few studies evaluating the key features of real-time interaction in other domains. This article attempts to address this situation by proposing a new approach to the concept of real-time interaction driving the analysis of this topic into paradigmatic cases studies in new media, video games and digital artworks. This new analysis reveals several specific facets that allow us to identify new factors in the understanding of this fuzzy concept. Finally, the article proposes a new definition of ‘real-time interaction’ based on the findings in the context of new media practices.     

A Cascaded Approach to Mention Detection and Chaining in Arabic

This paper presents a fully statistical approach to Arabic mention detection and chaining system, built around the maximum entropy principle. The presented system takes a cascade approach to processing an input document, by first detecting mentions in the document and then chaining the identified mentions into entities. Both system components use a common maximum entropy framework, which allows the integration of a large array of feature types, including lexical, morphological, syntactic, and semantic features. Arabic offers additional challenges for this task (when compared with English, for example), as segmentation is a needed processing step, so one can correctly identify and resolve enclitic pronouns. The system presented has obtained very competitive performance in the automatic content extraction (ACE) evaluation program.      

Recognising symmetry in solid models

Although the symmetry of solids has been studied for over 50 years, it is still not easy to find a method for detecting symmetry in objects represented by B-rep solid models documented in the literature. The need for such a method comes from the requirements of an environment for ‘Assembly Oriented Design’ which includes ‘Design for Assembly’ analyses. This paper begins with definition of terminology used to describe the different types of symmetry that may occur in components and then gives a detailed review in which the benefits and limitations of the many existing methods used for symmetry detection in other applications are discussed. Since none of the methods appear to provide a solution, which can be easily adapted to the Assembly Oriented Design application, the requirements of any new method are then more precisely identified. It appears that human perception of symmetry is considerably more robust than any computational method in existence and therefore the cognitive processes involved in human symmetry detection are examined to attempt to identify promising directions for an alternative approach. As a result of this study, a new method for symmetry detection, which uses the comparison of face loops has been devised. This proves to be an effective technique for the detection of symmetry, which also satisfies the requirements of the particular application. One implementation of a procedure is described in detail together with results of its use on several test cases. Finally, since this method has a demanding practical application, the computational efficiency of the method is examined at length.     

Morphological corner detector using paired triangular structuring elements

This paper describes corner detection from segmented areas using mathematical morphology employing paired triangular structuring elements. The algorithm identified as TriSE02 detects the inner corners of a segmented area and stores information regarding each corner's angular orientation and position. The theoretical development of this detector together with its empirical performance is established in a test utilising standard template images. Seven other established corner detectors were also tested to provide comparative performance information. This work was originally developed to identify conjugate corners in stereoscopic dual-energy X-ray images produced by an experimental system for aviation security screening. The oversensitivity exhibited by the established detectors when applied to the dual-energy X-ray images has been significantly improved upon by the new detector. Also, the careful development of the default parameterisation has resulted in a flexible approach, which is suitable for different image types and formats.     

An approach to clone detection in sequence diagrams and its application to security analysis

Duplication in software systems is an important issue in software quality assurance. While many methods for software clone detection in source code and structural models have been described in the literature, little has been done on similarity in the dynamic behaviour of interactive systems. In this paper, we present an approach to identifying near-miss interaction clones in reverse-engineered UML sequence diagrams. Our goal is to identify patterns of interaction (“conversations”) that can be used to characterize and abstract the run-time behaviour of web applications and other interactive systems. In order to leverage existing robust near-miss code clone technology, our approach is text-based, working on the level of XMI, the standard interchange serialization for UML. Clone detection in UML behavioural models, such as sequence diagrams, presents a number of challenges—first, it is not clear how to break a continuous stream of interaction between lifelines (representing the objects or actors in the system) into meaningful conversational units. Second, unlike programming languages, the XMI text representation for UML is highly non-local, using attributes to reference-related elements in the model file remotely. In this work, we use a set of contextualizing source transformations on the XMI text representation to localize related elements, exposing the hidden hierarchical structure of the model and allowing us to granularize behavioural interactions into conversational units. Then we adapt NICAD, a robust near-miss code clone detection tool, to help us identify conversational clones in reverse-engineered behavioural models. These conversational clones are then analysed to find worrisome interactions that may indicate security access violations.     

Modeling and querying moving objects in networks

Moving objects databases have become an important research issue in recent years. For modeling and querying moving objects, there exists a comprehensive framework of abstract data types to describe objects moving freely in the 2D plane, providing data types such as moving point or moving region. However, in many applications people or vehicles move along transportation networks. It makes a lot of sense to model the network explicitly and to describe movements relative to the network rather than unconstrained space, because then it is much easier to formulate in queries relationships between moving objects and the network. Moreover, such models can be better supported in indexing and query processing. In this paper, we extend the ADT approach by modeling networks explicitly and providing data types for static and moving network positions and regions. In a highway network, example entities corresponding to these data types are motels, construction areas, cars, and traffic jams. The network model is not too simplistic; it allows one to distinguish simple roads and divided highways and to describe the possible traversals of junctions precisely. The new types and operations are integrated seamlessly into the ADT framework to achieve a relatively simple, consistent and powerful overall model and query language for constrained and unconstrained movement.     

Thermography based breast cancer analysis using statistical features and fuzzy classification

Medical thermography has proved to be useful in various medical applications including the detection of breast cancer where it is able to identify the local temperature increase caused by the high metabolic activity of cancer cells. It has been shown to be particularly well suited for picking up tumours in their early stages or tumours in dense tissue and outperforms other modalities such as mammography for these cases. In this paper we perform breast cancer analysis based on thermography, using a series of statistical features extracted from the thermograms quantifying the bilateral differences between left and right breast areas, coupled with a fuzzy rule-based classification system for diagnosis. Experimental results on a large dataset of nearly 150 cases confirm the efficacy of our approach that provides a classification accuracy of about 80%.