A non-standard semantics for program slicing and dependence analysis

We introduce a new non-strict semantics for a simple while language. We demonstrate that this semantics allows us to give a denotational definition of variable dependence and neededness, which is consistent with program slicing. Unlike other semantics used in variable dependence, our semantics is substitutive. We prove that our semantics is preserved by traditional slicing algorithms.     

Multi-metaphor method: organizational metaphors in information systems development

Abstract.  Conventional methods have been criticized for their positivist philosophy and for either ignoring the organizational context of information systems development (ISD) or using only a simplistic, machine-based conceptual model of organizations. We have developed an approach to enable systems developers to use a richer view of organizations and a more interpretive approach. Multi-Metaphor Method (MMM) supports developers via a range of metaphors as cognitive structuring devices to understand an organization so that developers can learn to move between different ways of 'reading' the social context in which ISD occurs. We explain the rationale and theoretical underpinnings of MMM and then discuss our action research to investigate the viability and relevance of MMM during ISD practice. We show how the developers' use of organizational metaphors via MMM did not just enable rich conceptualizations of the client organizations but also influenced the ISD process and final product. We review the learning outcomes and discuss the implications for systems development practice of our research.     

Analyzing place metaphors in 3D educational collaborative virtual environments

In the recent years, the usage of three dimensional (3D) collaborative virtual environments (CVEs) for educational purposes has increased. The metaphors behind the design of virtual places are quite diverse, from replication of real universities to art museums and scientific labs. This paper reports the results of a case study where the students of our university, as a part of their course assignment, analyzed place metaphors used in a range of 3D educational CVEs vs. the corresponding educational goals. The students suggested a design for a virtual campus representing the Norwegian University of Science and Technology (NTNU). The results of this study provide some suggestions concerning the characterization of different design features in educational CVEs and the suitability of such features for different educational goals. Also, a preliminary set of design guidelines for an ideal virtual campus representing a real university is presented. Finally, some challenges associated with using 3D CVEs in various educational situations are discussed.     

A program for generating configuration state lists in many-electron atoms

This program written in FORTRAN is aimed at generating configuration state list of the set of complex atomic configurations. The program generates a list of configuration states obtained by taking into account many additional constraints of different types for minimizing the orders of matrices, as proposed in [Bogdanovich et al., Comput. Phys. Comm. 143 (2002) 174]. The generated list file complies with the requirements of codes [Hibbert et al., Comput. Phys. Comm. 64 (1991) 455; Fischer et al., Comput. Phys. Comm. 64 (1991) 486] and other related programs.

Program summary

Title of program: ATOTERMCatalogue identifier: ADTMProgram summary URL:http://cpc.cs.qub.ac.uk/summaries/ADTMProgram obtainable from: CPC Program Library, Queen's University of Belfast, N. IrelandLicensing provisions: NoneComputers: Any computer with a FORTRAN 77 compilerOperating systems under which the program has been tested: LinuxProgramming language used: FORTRAN 77Memory required to execute with typical data: 2 MBNo. of lines in distributed program, including text data, etc.: 2368No. of bytes in distributed program, including test data, etc.: 15 446Distribution format: tar gzip fileKeywords: Complex atom, configuration interaction, configuration state, LS-couplingNature of physical problem: Generating the list of configuration states with taking into account multiple additional constraints of different types.Method of solution: Building the configuration state list for the set of the given configurations with further selection of necessary configuration states by applying a set of restrictions on each configuration.Restrictions onto the complexity of the problem: For atomic configurations containing any electron shells with l?3; momenta of the electron shells with l>3 and N?2 is restricted by L_max=6. The number of the active shells can not exceed seven.Unusual features of the program: Possibility to select configuration states.Typical running time: Seconds to minutes. Depends on the size of the problem: of the order of a few seconds for simple configurations to minutes for a large set of very complex admixed configurations with f-electron shells.     

JJGEN: A flexible program for generating lists of jj-coupled configuration state functions

The success of large scale relativistic multiconfiguration Dirac-Hartree-Fock calculations for atomic systems rely on judiciously chosen configuration expansions. Dependent on the atomic system as well as on the studied properties, various correlation effects need to be considered. Based on the active set approach, this program allows the user to generate general lists of jj-coupled configuration state functions to be used as input to the grasp2K multiconfiguration Dirac-Hartree-Fock package [P. Jönsson, X. He, C. Froese Fischer, I.P. Grant, Comput. Phys. Comm. (2007), in press].

Program summary

Program title: JJGENCatalogue identifier: ADZG_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADZG_v1_0.htmlProgram obtainable from: CPC Program Library, Queen's University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 10 673No. of bytes in distributed program, including test data, etc.: 430 543Distribution format: tar.gzProgramming language: FortranComputer: Intel compatible PCOperating system: Linux, UnixWord size: 32 bitsClassification: 7.3Nature of problem: Generation of lists of jj-coupled configuration state functions to describe different electron correlation effects in many-electron atoms.Solution method: From a set of reference configurations a list of jj-coupled configuration state functions is generated by excitations to an active set of orbitals. Imposing restrictions on the allowed excitations the configuration expansion can be targeted to describe different correlation effects.Restrictions: The complexity of the cases that can be handled is entirely determined by the grasp2K package [P. Jönsson, X. He, C. Froese Fischer, I.P. Grant, Comput. Phys. Comm. (2007), in press] used for the generation of the electronic wave-functions.Running time: CPU time required to execute test cases: few seconds.     

Providing proper affordances when transferring source metaphors from information appliances to a 3G mobile multipurpose handset

The idea of merging different information appliances, each tailored to fit a specific task, into a multipurpose 3G mobile handset has become an interesting research area. This paper describes what considerations must be met from an efficiency point of view when designing a multipurpose handset concept including, e.g., camera functionality. The lessons learned when trading well-known previously acquired source metaphors for the computer metaphor was investigated in a small usability evaluation with 14 users, evaluating a multipurpose prototype. High task accuracy (effectiveness) was obtained (72% pass), but the efficiency with which the tasks were performed compared to using dedicated information appliances was low. Leaving out well-known affordances effectively prevented transfer of previously acquired source metaphors, which resulted in lack of feedback, inconsistency and errors. In order to validate usability, a combination of both objective and subjective metrics has to be used.     

A compact fixpoint semantics for term rewriting systems

This work is motivated by the fact that a “compact” semantics for term rewriting systems, which is essential for the development of effective semantics-based program manipulation tools (e.g. automatic program analyzers and debuggers), does not exist. The big-step rewriting semantics that is most commonly considered in functional programming is the set of values/normal forms that the program is able to compute for any input expression. Such a big-step semantics is unnecessarily oversized, as it contains many “semantically useless” elements that can be retrieved from a smaller set of terms. Therefore, in this article, we present a compressed, goal-independent collecting fixpoint semantics that contains the smallest set of terms that are sufficient to describe, by semantic closure, all possible rewritings. We prove soundness and completeness under ascertained conditions. The compactness of the semantics makes it suitable for applications. Actually, our semantics can be finite whereas the big-step semantics is generally not, and even when both semantics are infinite, the fixpoint computation of our semantics produces fewer elements at each step. To support this claim we report several experiments performed with a prototypical implementation.     

A rule-based system for generating a ladder logic control program from a high-level systems model

In this article an interface between a high-level specification of a system and a logic controller of that system is developed. The interface is based on a number of rules to transform an IDEF0 specification into an intermediate-level Petri-net-based controller and to transform the intermediate specification into a ladder logic program which can be run on a PLC. These rules could be used as a basis for developing an expert system to handle the interface. Such an expert system provides an environment for rapid prototyping and analysis of controllers.     

A Game Semantics for Grz

We present a game semantics for modal propositional logic Grz.Since intuitionistic logic may be embedded into Grz, the semanticsalso covers intuitionistic propositional logic. That semanticsis simpler than Lorenzen's ‘dialogue’ games, butlacks predicates.     

Concurrent Logic and Automata Combined: A Semantics for Components

In this paper, we describe a true-concurrent hierarchical logic interpreted over concurrent automata. Concurrent automata constitute a special kind of asynchronous transition system (ATS) used for modelling the behaviour of components as understood in component-based software development. Here, a component-based system consists of several interacting components whereby each component manages calls to and from the component using ports to ensure encapsulation. Further, a component can be complex and made of several simpler interacting components. When a complex component receives a request through one of its ports, the port delegates the request to an internal component. Our logic allows us to describe the different views we can have on the system. For example, the overall component interactions, whether they occur sequentially, simultaneously or in parallel, and how each component internally manages the received requests (possibly expressed at different levels of detail). Using concurrent automata as an underlying formalism we guarantee that the expressiveness of the logic is preserved in the model. In future work, we plan to integrate our truly-concurrent approach into the Edinburgh Concurrency Workbench.     

一种面向对象测试用例自动生成的混合算法*

遗传算法(GA)在测试用例生成方面是一种实用的算法,但是其自身也存在的局限性,如过早收敛、优化效率低等问题.通过引入粒子群算法(PSO),使每一个测试用例在局部区域中再次寻找最优值,以此改进整体算法搜索最佳值的能力,避免过早收敛、优化效率低的问题.与此同时,针对面向对象测试的特点,如封装性等,将混合算法进行适当的改进,满足在不同环境中重复使用类的要求.     

Tagged Systems: A Framework for the Specification of History-dependent Properties

We propose a general method for the treatment of history-dependent runtime errors. When one has to control this kind of errors, a tagged version of the language is usually defined, in which tags capture only the necessary information of the history of processes. We will characterize such tagged languages as being quotients of the reachability tree defined by the computations of the original language. From this fact we can conclude that the property characterized by each tagged language is indeed a property of the original one. In this way, we can work in a common framework, instead of defining an ad hoc semantics for each property. In particular, we could still use the analysis machinery existing in the calculus in order to prove that or other related properties. We have applied this methodology to the study of resource access control in a distributed π-calculus, called Dπ. In particular, we have proved that the tagged version of Dπ is indeed a tagging according to our definition.     

HYLAS: program for generating H curves (abstract three-dimensional representations of long DNA sequences)

The computer program HYLAS generates from a standard DNA letter sequence a three-dimensional space curve (H curve) which embodies the entire information content of the original nucleotide sequence. The program can display H curves either as two-dimensional (front and side view) projections or as stereo-pair images. The curves can be marked at specific nucleotide locations, annotated, rotated for observation from any viewing angle, and manipulated for convenient side-by-side comparisons. Unlike the cumbersome letter sequences, H curves can be drastically condensed in size without losing their ability to reflect the global nucleotide-distribution pattern of the entire DNA sequence. Often, biologically important loci can be visually identified on the H curves. HYLAS is written in FORTRAN with separate mainframe (IBM-VM/CMS) and microcomputer (MS-DOS) versions. It uses the Tektronix-TCS library of graphic subroutines.