XML is becoming one of the most influential standards concerning data exchange and Web-presentations. In this paper we present a visual language for querying and transforming XML data. The language is based on a visual document metaphor and the notion of document patterns. It combines an intuitive, dynamic form-based interface for defining queries and transformation rules with powerful pattern matching capabilities and offers thus a highly expressive yet easy to use visual language. Providing visual language support for XML not only helps end users, it is also a big opportunity for the VL community to receive greater attention. 1 Introduction The eXtensible Markup Language (XML) is a standardized notation for documents and other data [3]. It is very likely that XML develops into the prevailing format for exchanging documents and presenting data in the WorldWide Web. An XML document contains, in addition to its content, information about its structure, which is achieved through tagge...

We present a visual language for querying and transforming XML data. The language is based on a visual document metaphor and the notion of document patterns and rules. It combines a dynamic form-based interface for defining queries and transformation rules with powerful pattern matching capabilities and offers thus a highly expressive visual language. The design of the visual language is specifically targeted at end users.

We propose a new style of writing graph algorithms in functional languages which is based on an alternative view of graphs as inductively defined data types. We show how this graph model can be implemented efficiently, and then we demonstrate how graph algorithms can be succinctly given by recursive function definitions based on the inductive graph view. We also regard this as a contribution to the teaching of algorithms and data structures in functional languages since we can use the functional-style graph algorithms instead of the imperative algorithms that are dominant today. Keywords: Graphs in Functional Languages, Recursive Graph Algorithms, Teaching Graph Algorithms in Functional Languages

We propose a form-based interface to expresses XML queries and transformations by so-called "document patterns" that describe properties of the requested information and optionally specify how the found results should be reformatted or restructured. The interface is targeted at casual users who want a fast and easy way to find information in XML data resources. By using dynamic forms an intuitive and easy-to-use interface is obtained that can be used to solve a wide spectrum of tasks, ranging from simple selections and projections to advanced data restructuring tasks. The interface is especially suited for end users since it can be used without having to learn a programming or query language and without knowing anything about (query or XML) language syntax, DTDs or schemas. Nevertheless, DTDs can be well exploited, in particular, on the user interface level to support the semi-automatic construction of queries.

In order to define the semantics of diagram languages, new techniques may be developed following the established approaches of denotational, operational, or algebraic semantics of programming languages. Due to the multi-dimensional nature of diagrams (as opposed to the linear structure of programs), these new approaches should be based on graphs (rather than trees or terms) and graph transformation could provide the underlying technology. In this paper, we try to substantiate this claim by reviewing some of the most important approaches to semantics and discussing their applicability to diagram languages. Keywords diagram languages, semantics, graph transformation 1 Introduction The most important means for communication is the use of language. The language can be a natural one - like in human-human communication - or an artificial one - as in human-computer or computer-computer communication. In general, in the case of speaking, writing, or reading, the symbols in the la...

As visual programming languages become both more expressive and more popular in the domains of real-time and embedded software, the need for rigorous techniques for rea-soning about programs written in these languages becomes more pressing. Indeed, due to a subtle but fundamental mismatch between graphical and textual representations of pro-grams, semantic concepts established in the textual setting cannot be mapped to the graph-ical setting without a careful analysis of the connection between the two representations. Focusing on operational (as opposed to type-theoretic) aspects of Resource-aware Pro-gramming (RAP), we analyze the connection between graphical and textual representations of programs that can express both higher-order functions and staging constructs. After es-tablishing a precise connection between the two, we illustrate how this connection can be used to lift a reduction semantics from the textual to the graphical setting. I am very grateful for the dedication and support I received from my advisor Dr. Walid Taha while working on this thesis. I also want to thank the members of my thesis committee (Dr. Keith Cooper, Dr. Robert Cartwright, Dr. Peter Druschel, and Dr. Moshe Vardi) for their time and their interest in my work. Kedar Swadi, Samah Abu Mahmeed, and Roumen

Visual notations are pervasive in circuit design, control systems, and increasingly in mainstream programming environments. Yet many of the foundational advances in programming language theory are taking place in the context of textual notations. In order to map such advances to the graphical world, and to take the concerns of the graphical world into account when working with textual formalisms, there is a need for rigorous connections between textual and graphical expressions of computation. To this end, this paper presents a graphical calculus called Uccello. Our key insight is that Ariola and Blom’s work on sharing in the cyclic lambda calculus provides an excellent foundation for formalizing the semantics of graphical languages. As an example of what can be done with this foundation, we use it to extend a graphical language with staging constructs. In doing so, we provide the first formal account of sharing in a multi-stage calculus. 1.

Abstract. We propose a new focus in language design where languages provide constructs that not only describe the computation of results, but also produce explanations of how and why those results were obtained. We posit that if users are to understand computations produced by a language, that language should provide explanations to the user. As an example of such an explanation-oriented language we present a domain-specific language for explaining probabilistic reasoning, a domain that is not well understood by non-experts. We show the design of the DSL in several steps. Based on a story-telling metaphor of explanations, we identify generic constructs for building stories out of events, and obtaining explanations by applying stories to specific examples. These generic constructs are then adapted to the particular explanation domain of probabilistic reasoning. Finally, we develop a visual notation for explaining probabilistic reasoning. 1

The goal of the thesis is to solve the task of defining a flexible query language for distributed structured and semistructured data and to implement this language. For example, data can be represented as HTML files in the file system, whereby an XML document contains metadata about these files. Hence, these two data sources have to be merged appropriately. In order to satisfy the needs of the heterogeneous group of users, a flexible adaptable query language is required. Therefore a query model is developed which serves as a basis for an abstract syntax for query languages; this abstract syntax can be translated in concrete textual as well as graphical query languages. An implementation of the ideas proposed in the thesis is done in the area of virtual courses, especially in the project "Virtual University of Applied Sciences". 1

I linguaggi di specifica del comportamento di agenti, e pi uin generale di sistemi reattivi, spesso utilizzano notazioni grafiche per esprimere le configurazioni significative dello stato dell'agente e le trasformazioni ammissibili di tali configurazioni. L'espressione dei due aspetti puo essere delegata a diversi tipi di diagrammi, o venire incorporata in un unico diagramma. Inoltre, si possono sviluppare diagrammi comportamentali per diverse componenti del sistema, eventualmente impiegando diagrammi di tipo diverso per ogni sottosistema. A un livello astratto, tutti questi diagrammi esprimono qualche forma di trasformazione del sistema, che puo essere caratterizzata esprimendone le pre- e post-condizioni, e una politica di esecuzione delle trasformazioni. In questo lavoro, proponiamo un approccio uniforme alla gestione di transizioni, indipendente dalla notazione diagrammatica adottata, e che puo essere usata per stabilire corrispondenze tra modifiche della rappresentazione visuale e trasformazioni del modello sottostante.