14174107
Lifting in Z
Formal notations such as Z provide powerful support for writing clear specifications, and for undertaking proofs of properties of those specifications. In this paper, we explore one particular style of specification, with applications in control theory and real-time specification. The notation we define permits the accurate description of concepts in these fields without significant overhead or notational clutter. This notation has long been used by practitioners in these fields; we demonstrate that it may be defined within Draft Standard Z, and that the resulting specifications are amenable to proof.
26464031
A Taxonomy of Web Services Using CSP
Terms such as conversational and stateless are widely used in the taxonomy of web services. We give formal definitions of these terms using the CSP process algebra. Within this framework we also define the notion of Service-Oriented Architecture. These definitions are then used to prove important scalability properties of stateless services. The use of formalism should allow recent debates, concerning how and whether web services provide standardized access to state, to progress more rigorously.
6469757
Teaching Formal Methods in Context
The Software Engineering Programme at Oxford teaches formal methods as an integral part of its programme of professional education in software engineering. This paper explains how the methods are taught—in the context of emerging trends in software development, and in the context of existing practice—and how their use is promoted through course design and motivating examples.
17355175
Packing Steiner Trees: Separation Algorithms
In this paper, we investigate separation problems for classes of inequalities valid for the polytope associated with the Steiner tree packing problem, a problem that arises, e.g., in very large-scale integration (VLSI) routing. The separation problem for Steiner partition inequalities is \NP-hard in general. We show that it can be solved in polynomial time for those instances that come up in switchbox routing. Our algorithm uses dynamic programming techniques. These techniques are also applied to the much more complicated separation problem for alternating cycle inequalities. In this case, we can compute in polynomial time, given some point $y$, a lower bound for the gap $\alpha-a^Ty$ over all alternating cycle inequalities $a^Tx\ge\alpha$. This gives rise to a very effective separation heuristic. A by-product of our algorithm is the solution of a combinatorial optimization problem that is interesting in its own right: find a shortest path in a graph where the "length" of a path is its usual length minus the length of its longest edge.
34039430
A model of information systems development project performance
. Performance in information systems development (ISD) projects can be critical to business success. But, while project performance has been the subject of much debate, there has been little empirical research into its determinants. A survey of IS projects in the UK and New Zealand is analysed to test hypotheses concerning performance in terms of both project completion and budget (time-cost) variances. Subsequently, a secondary analysis of the findings is used to build a more complete empirical model of project performance. The paper helps to develop the theory of IS development project performance and also has significant implications for practice. Discussion of the findings highlights the importance of project team dynamics, risk management, senior management support for strategic projects and user participation in ensuring successful IS project performance.
14479325
Bus catcher: a context sensitive prototype system for public transportation users
In this paper we describe the architectural andfunctional characteristics of Bus Catcher, a contextsensitive prototype system for public transportation users.Bus Catcher assists mobile users in planning their busrides by providing timely and accurate information aboutcurrent bus locations and estimated arrival times. Acomplete report on the implementation together with apreliminary evaluation of the system is provided in thispaper.
18494896
The steiner tree packing problem in VLSI design
In this paper we describe several versions of the routing problem arising in VLSI design and indicate how the Steiner tree packing problem can be used to model these problems mathematically. We focus on switchbox routing problems and provide integer programming formulations for routing in the knock-knee and in the Manhattan model. We give a brief sketch of cutting plane algorithms that we developed and implemented for these two models. We report on computational experiments using standard test instances. Our codes are able to determine optimum solutions in most cases, and in particular, we can show that some of the instances have no feasible solution if Manhattan routing is used instead of knock-knee routing.
10076896
Agent Assistance for 3D World Navigation
This paper presents mechanisms and approaches to assist user navigation and exploration within 3-dimensional worlds. Specifically, we advocate the deployment of an agent based approach for dynamic system assistance and intervention. An algorithm has been developed, that produces a performance measure, which is employed by the intelligent agent to activate system interventions. We outline the importance of providing discrete navigational cues to users in order to increase their sense of immersion and their overall satisfaction while working within the 3D world. We present HADES - the Home of the Adaptive Environmental System, which is a 3-dimensional world within which the intelligent agent is immersed. The agent therefore has the ability to transform this 3D world into an intelligent environment. HADES reacts proactively to users' movements and offers navigational help indirectly. Indirect navigational support increases the user's satisfaction with his own performance and therefore endorses the user's sense of immersion.