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.
15745921
Wireless networks and random geometric graphs
In this paper, mobile ad-hoc networks are studied. Chen and Jia (2001) proposed a routing algorithm by utilizing multiple communication channels and localizing the routing information (routing tables) for mobile stations within the wireless network. The routing algorithm relies on a spanning tree of the underlying network. It is proven that both the construction of the spanning tree and the routing algorithm are efficient. The routing algorithm is also reliable because of the frequent update of the spanning tree which the routing scheme is based on. The underlying network is a random geometric graph G(A,n) formed on a set of uniformly randomly located points in the unit disk, in which two vertices are adjacent if and only if their Euclidean distance is at most A.
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.
16011778
A Uniform System for Publishing and Maintaining XML Data
XML has become the prime standard for data exchange on the Web. To exchange data residing in Databases, one needs to publish it in XML. Data publishing is often done with a predefined “schema.” The chapter proposes a new approach for schema-directed publishing of relational data in XML, based on the novel notion of attribute transformation grammars (ATGs). ATGs provide guidance on how to define views conforming to target schemas (DTDs), and automatically ensure schema conformance. The chapter also develops an incremental algorithm for maintaining XML views produced by ATGs, based on new incremental computation techniques that capitalize on the hierarchical structure of XML data and unique features of the ATGs. Taking real-life data from Gene Ontology (GO), this chapter also demonstrates how this system can efficiently publish the GO data in XML with respect to a predefined recursive DTD, and how it incrementally updates the target XML data in response to changes to the underlying GO database.
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.
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.