42442258
An approach to animating Z specifications
This paper presents the ZANS approach to animating a large subset of Z specifications. Unlike most other animation approaches that are based on functional or logical programming paradigms, the approach presented transforms the specifications into an imperative intermediate language, which can also serve as the basis of code synthesis from Z specifications. ZANS is showing promise of being an effective tool for requirements validation and assisting students learning Z specification languages.
22388831
PROOF: A Parallel Object-Oriented Functional Computation Model
Abstract Despite the rapid development of parallel computer architectures in recent years, software development technology for parallel processing systems is still largely inadequate. An integrated object-oriented and functional computation model, called PROOF, is developed to facilitate the effective development of software for parallel processing systems. It will fully explore the parallelism in software systems and reduce the development effort by supporting software engineering principles, such as information hiding, modularity, modifiability, and reusability. In PROOF, we achieve the coherent integration of (1) parallelism and inheritance of objects and (2) referential transparency and history sensitivity of functions. The major features and the semantics of PROOF are presented. A parallel programming language and a software development approach based on PROOF are under development. Implementation issues are also discussed.
13944177
A pragmatic approach to formalizing object-oriented modeling and development
Despite recent developments in formal methods, these methods have yet to enter the mainstream of the software industry. We first examine the pragmatic obstacles to making formal methods practical and usable. Then we present a pragmatic approach to integrate a popular object oriented modeling notation UML and a popular formal notation Z. Our approach is distinctive in its emphasis on overcoming the practical obstacles. We also present a light weight supporting tool for our approach. A prototype of the supporting tool is completed. It allows us to demonstrate the feasibility and capability of our approach.
44437581
Visual languages and software specifications
The important issues and major features of visual languages are summarized, and their impact on software engineering, especially software specification techniques, are discussed. The potential of using visual languages for software specifications to improve software reliability, modifiability, reusability, and understandability is also considered.<<ETX>>
223086
Detecting null pointer violations in Java programs
The use of formal methods has been growing steadily and there have been a number of successful applications of formal methods in a range of application areas. It seems agreed that quality should be assured by applying testing, analysis and formal methods to rigorously defined precode artifacts. The detection of null pointer violation errors is definitely such a goal. This way of applying formal methods has a great potential to increase our confidence in the software. Our goal is to provide a practical mechanism to assist the application of formal methods in the early detection of null pointer violation errors in programs. Our solution is theorem proving based and is focused on the identification of the possible places in which a theorem prover could assist in the detection of null pointer violation errors and the formulation of the necessary proof obligations.
2524138
Code synthesis based on object-oriented design models and formal specifications
Presents an approach to synthesizing functional and robust code from object-oriented design models and Z data and operation specifications. The approach used is based on an integrated notation of the Unified Modeling Language (UML) and a slightly extended Z notation to include object-oriented concepts and structures. Our approach generates fully functional code which can be compiled and executed without modifications. The information from object-oriented analysis and design models along with the formal specifications are combined, analyzed and translated into an intermediate representation from which code can be generated. A research prototype has been developed to demonstrate the feasibility and the effectiveness of our approach.
17179157
Conditional Functional Dependencies for Data Cleaning
We propose a class of constraints, referred to as conditional functional dependencies (CFDs), and study their applications in data cleaning. In contrast to traditional functional dependencies (FDs) that were developed mainly for schema design, CFDs aim at capturing the consistency of data by incorporating bindings of semantic ally related values. For CFDs we provide an inference system analogous to Armstrong's axioms for FDs, as well as consistency analysis. Since CFDs allow data bindings, a large number of individual constraints may hold on a table, complicating detection of constraint violations. We develop techniques for detecting CFD violations in SQL as well as novel techniques for checking multiple constraints in a single query. We experimentally evaluate the performance of our CFD-based methods for inconsistency detection. This not only yields a constraint theory for CFDs but is also a step toward a practical constraint-based method for improving data quality.
2884321
Some remarks on minimal bases and maximal nonbases of integers
Abstract In this note, we generalize the concepts of minimal bases and maximal nonbases for integers, and prove some existence theorems for the generalized minimal bases and maximal nonbases, which generalize some results of Stohr, Deza and Erdos, and Nathanson.
41488878
On a Network Sensing Problem
Live traffic flow information can help improve the efficiency of a communication network. There are many ways available to monitor the traffic flow of a network. In this paper, we propose a very efficient monitoring strategy. This strategy not only reduces the number of nodes to be monitored but also determines the complete traffic information of the entire network using the information from the monitored nodes. The strategy is optimal for monitoring a network because it reduces the number of monitored nodes to a minimum. Fast algorithms are also presented in this paper to compute the traffic information for the entire network based on the information collected from the monitored nodes. The monitoring scheme discussed in this paper can be applied to the internet, telecommunication networks, wireless ad hoc networks, large scale multiprocessor computing systems, and other information systems where the transmission of information needs to be monitored.
6166247
Virtual backbone construction in multihop ad hoc wireless networks
Summary Recent research points out that the flooding mechanism for topology update or route request in existing ad hoc routing protocols greatly degrades the network capacity. If we restrict the broadcast of control packets within a small subset of hosts in the network, the protocol overhead can be substantially reduced. This motivates our research of constructing a virtual backbone by computing a connected dominating set (CDS) in unit-disk graphs. In this paper, we propose two distributed algorithms to approximate a minimum CDS. These algorithms take linear time. Their performance is verified by a complete theoretical analysis. Copyright # 2006 John Wiley & Sons, Ltd.
28697957
The maximum size of graphs satisfying a degree condition
Let G be a simple graph of order n without isolated vertices. If the integer h satisfies 
h ⩾ maxυ ϵ V(G)minu ψ N(V)(degGu) 
then G is called an Fn(h)-graph. In this note the maximum size of Fn(h)-graphs is determined. A result of Krol and Veldman on critically h-connected graphs follows as a corollary.