Algorithm visualization (AV) technology graphically illustrates how algorithms work. Despite the intuitive appeal of the technology, it has failed to catch on in mainstream computer science education. Some have attributed this failure to the mixed results of experimental studies designed to substantiate AV technology's educational effectiveness. However, while several integrative reviews of AV technology have appeared, none has focused specifically on the software's effectiveness by analyzing this body of experimental studies as a whole. In order to better understand the effectiveness of AV technology, we present a systematic metastudy of 24 experimental studies. We pursue two separate analyses: an analysis of independent variables, in which we tie each study to a particular guiding learning theory in an attempt to determine which guiding theory has had the most predictive success; and an analysis of dependent variables, which enables us to determine which measurement techniques have been most sensitive to the learning benefits of AV technology. Our most significant finding is that how students use AV technology has a greater impact on effectiveness than what AV technology shows them. Based on our findings, we formulate an agenda for future research into AV effectiveness.

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: In this paper, we focus on the design and the implementation of a query language, Cigales, for Geographical Information Systems. This language is based on a visual and declarative Query-ByExample philosophy. The semantics of an end-user query is expressed by a drawing. We present the querying philosophy of the Cigales language. To take into account the particularities of the visual query language and the geographical data, we introduce several extensions to the classical database models (i.e., the icons, the variables, the overlap of the spatial representation). To illustrate the concepts of the Cigales language, we provide the representation of several queries (involving a unique "object," two "objects" without operators, two "objects" linked with a spatial operator, several "objects" linked with several spatial operators). Since the design of a user interface is an iterative process, the implementation is still going on and we present the current state of the CIGALES prototype. Key...

: Operators for geographical databases can be classified into two categories: thematic-oriented operators and network-oriented operators. Thematic-oriented operators are based on geometric representations (e.g., intersection, inclusion, adjacency). Network-oriented operators are based on graph manipulations whatever the geometric representation is (e.g., a transitive closure of a graph). In this paper we present network manipulations with a visual query language for a geographical database. A query is defined with a visual expression defined with a Query-By-Example approach. The user draws a graphic representing the properties results have to verify. Keyword: Visual query language, Graph manipulations, Geographical Information System I. INTRODUCTION In current research toward the design of more powerful tools for urban planning and remote sensing, different research groups are simultaneously concentrating their work on Geographical Information Systems (GIS). GIS needs are very well kno...

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This paper presents the links between a visual programming language, Cigales, and a database management system in the context of a Geographical Information System. We study the way of filling the gap between the semantic level of a visual query language and a data base query language. 1. INTRODUCTION In the current research toward the design of more powerful tools for urban planning, remote sensing, ... different research groups are simultaneously concentrating their work on Geographical Information System (GIS). GIS needs are very well known [6]. Several problems are still open. In this paper we focus on the design of a user-friendly query language. Designing the user interface is one of the main issues to deal with when building spatial information systems. It will be increasingly true since geographic information is now affecting such general applications as tourism and nonspecialist users. The visual (or graphical) query language concept appeared with the development of "cheap" gra...

: In this paper, we analyze the various philosophies to define a query language for geographical database. The differences among the three possibilities of extending the SQL language rely on the definition of the clause Select: (1) the clause Select does not accept a spatial operator and the Where clause accepts one (or several) predicate defined between attributes; (2) the clause Select accepts one (or several) spatial operator(s) with attributes as arguments; (3) the clause Select accepts one (or several) spatial operator(s) with attributes or other spatial operators as arguments. To guarantee a coherent result of a query, we present the requirements of these three philosophies. Key words: Geographical Information System, Spatial Database, Query Language, Extended SQL I. INTRODUCTION In the current research toward the design of more powerful tools for urban planning, remote sensing, ... different research groups are simultaneously concentrating their work on Geographical Informatio...

This paper describes the process of designing an authoring tool for virtual environments, using constructivist principles. The focus of the tool is on helping novice designers without coding experience to conceptualise and visualise the interactions of the virtual environment. According to constructivism, knowledge is constructed by people through interactions with their social and physical environments. Major aspects of this theory are explored, such as multiple representations, reflexivity, exploration, scaffolding and user control. Its practical application to the design of the tool is then described.

Previous work in software visualization has demonstrated the advantages of presenting programs in a graphical manner in both program understanding and debugging. Among the class of program visualization systems are those which operate non-intrusively on program sources. One of the major challenges faced by users of such systems is the problem of filtering the enormous amount of run-time information present during the execution of a large system. In this thesis, I describe an evolution of the Software Landscape. The Software Landscape is a tool for browsing a software system's static structure using boxes together with arrow and containment relations. My Run-Time Landscape includes run-time information, utilizes the Landscape paradigm for the elision of unwanted details, and provides a tightly integrated environment for viewing program artifacts from different perspectives. This prototype is useful in debugging, program understanding, and profiling. ii Acknowledgements I am grateful...

An investigation of visual strategies to help users design and implement interactions in 3D worlds PhD Research Proposal