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.
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>>
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.
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.
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.
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.
42148814
Using GALS architecture to reduce the impact of long wire delay on FPGA performance
19271257
Extremal Cayley Digraphs of Finite Cyclic Groups
Let $\cay(m,A)$ denote the Cayley digraph on ${\bf Z}_m$ generated by $A$, where ${\bf Z}_m$ is the cyclic group of residues modulo $m$. Let $r(m,A)$ denote the average distance of $\cay(m,A)$. For any $r\ge1$ and $k\ge1$ define $m^*(r,k)$ as the largest positive integer $m$ such that the average distance of the Cayley digraph $\hbox{Cay}(m,A)$ is at most $r$ for some set $A$ with $k$ elements. In this paper, an asymptotic formula for $m^*(r,2)$ is proved and a lower bound for $m^*(r,k)$ is also obtained for $k\ge3$. Applications to the construction of optimal distributed loop networks is discussed in this paper. A lower bound of the average order of subsets for asymptotic bases in number theory is proved using the main theorem of this paper.
18149163
SMOQE: a system for providing secure access to XML
XML views have been widely used to enforce access control, support data integration, and speed up query answering. In many applications, e.g., XML security enforcement, it is prohibitively expensive to materialize and maintain a large number of views. Therefore, views are necessarily virtual. An immediate question then is how to answer queries on XML virtual views. A common approach is to rewrite a query on the view to an equivalent one on the underlying document, and evaluate the rewritten query. This is the approach used in the Secure MOdular Query Engine (SMOQE). The demo presents SMOQE, the first system to provide efficient support for answering queries over virtual and possibly recursively defined XML views. We demonstrate a set of novel techniques for the specification of views, the rewriting, evaluation and optimization of XML queries. Moreover, we provide insights into the internals of the engine by a set of visual tools.