Giuseppe Polese

A framework for modeling and implementing visual notations with applications to software engineering

We present a framework for modeling visual notations and for generating the corresponding visual programming environments. The framework can be used for modeling the diagrammatic notations of software development methodologies, and to generate visual programming environments with CASE tools functionalities. This is accomplished through an underlying modeling process based on the visual notation syntactic model of eXtended Positional Grammars (XPG, for short), and the associated parsing methodology, XpLR. In particular, the process requires the modeling of the basic elements (visual symbols) of a visual notation, their syntactic properties, the relations between them, the syntactic rules to formally define the set of feasible visual sentences, and a set of semantic routines performing additional checks and translation tasks. Such a process is completely supported by the VLDesk system, which enables the automatic generation of an editor for drawing visual sentences, as well as a processor for their recognition, parsing, and translation into other notations.The proposed framework also provides the basis for the definition of a meta-CASE technology. In fact, we can customize the generated visual programming environment in terms of the supported visual notation, its syntactic properties, and the translation rules. We have used this framework to model several diagrammatic notations used in software development methodologies, including those of the Unified Modeling Language.

A Classification Framework to Support the Design of Visual Languages

Abstract An important step in the design of visual languages is the specification of the graphical objects and the composition rules for constructing feasible visual sentences. The presence of different typologies of visual languages, each with specific graphical and structural characteristics, yields the need to have models and tools that unify the design steps for different types of visual languages. To this aim, in this paper we present a formal framework of visual language classes. Each class characterizes a family of visual languages based upon the nature of their graphical objects and composition rules. The framework has been embedded in the Visual Language Compiler–Compiler (VLCC), a graphical system for the automatic generation of visual programming environments.

FIRST: Fractal Indexing and Retrieval SysTem for Image Databases

We present an image indexing method and a system to perform content-based retrieval in heterogeneous image databases (IDB). The method is based upon the fractal framework of the iterated function systems (IFS) widely used for image compression. The image index is represented through a vector of numeric features, corresponding to contractive functions (CF) of the IFS framework. The construction of the index vector requires a preliminary processing of the images to select an appropriate set of indexing features (i.e. contractive functions). The latter will be successively used to fill in the vector components, computed as frequencies by which the selected contractive functions appear inside the images. In order to manipulate the index vectors efficiently we use discrete Fourier transform (DFT) to reduce their cardinalities and use a spatial access method (SAM), like R*-tree, to improve search performances. The sound theoretical framework underlying the method enabled us to formally prove some properties of the index. However, for a complete validation of the indexing method, also in terms of effectiveness and efficacy, we performed several experiments on a large collection of images from different domains, which revealed good system performances with a low percentage of false alarms and false dismissals. q 1998 Elsevier Science B.V. All rights reserved.

A methodology and interactive environment for iconic language design

We describe a design methodology for iconic languages based upon the theory of icon algebra to derive the meaning of iconic sentences. The design methodology serves two purposes. First of all, it is a descriptive model for the design process of the iconic languages used in the Minspeak? systems for augmentative communication. Second, it is also a prescriptive model for the design of other iconic languages for human-machine interface. An interactive design environment based upon this methodology is described. This investigation raises a number of interesting issues regarding iconic languages and iconic communications.

Extended positional grammars

Positional grammars are a formalism for the definition and implementation of visual languages. They have already been used in the past as part of the VLCC system (Visual Language Compiler-Compiler) for the definition and the implementation of visual environments for editing and compiling flowcharts, chemical structures, combinatorial networks, electric circuits, etc. The authors introduce the eXtended Positional Grammars (XPG) that enhance the descriptive power of positional grammars. We also present a more powerful LR based methodology for parsing visual languages described by XPGs. The result is the possibility of describing and compiling a much wider class of visual languages, yet keeping most of the LR parsing efficiency.

A Parsing Technique for Sketch Recognition Systems

Several disciplines require the support of computer-based tools for creating sketches during early design phases. Unfortunately, most computer programs cannot parse and semantically interpret handwritten sketches. In this paper, we present a framework for modeling sketch languages and for generating parsers to recognize them. The underlying parsing technique addresses the issues of stroke clustering and ambiguity resolution in sketches. We also present a workbench supporting the presented framework

A SCORM Thin Client Architecture for E-Learning Systems Based on Web Services.

In this paper we propose an architecture of e-learning systems characterized by the use of Web Services and a suitable Middleware component. These technical infrastructures allow us to extend the system with new services as well as to integrate and reuse heterogeneous software e-learning components. Moreover, they let us better support the “anytime and anywhere” learning paradigm. �s a matter of fact, the proposal provides an implementation of the Run-Time Environment suggested in the Sharable Content Object Reference Model �SCORM�� to trace learning processes, which is also suitable for mobile learning.

Monitoring Online Tests through Data Visualization

We present an approach and a system to let tutors monitor several important aspects related to online tests, such as learner behavior and test quality. The approach includes the logging of important data related to learner interaction with the system during the execution of online tests and exploits data visualization to highlight information useful to let tutors review and improve the whole assessment process. We have focused on the discovery of behavioral patterns of learners and conceptual relationships among test items. Furthermore, we have led several experiments in our faculty in order to assess the whole approach. In particular, by analyzing the data visualization charts, we have detected several previously unknown test strategies used by the learners. Last, we have detected several correlations among questions, which gave us useful feedbacks on the test quality.

Relaxed Functional Dependencies—A Survey of Approaches

Recently, there has been a renovated interest in functional dependencies due to the possibility of employing them in several advanced database operations, such as data cleaning, query relaxation, record matching, and so forth. In particular, the constraints defined for canonical functional dependencies have been relaxed to capture inconsistencies in real data, patterns of semantically related data, or semantic relationships in complex data types. In this paper, we have surveyed 35 of such functional dependencies, providing a classification criteria, motivating examples, and a systematic analysis of them.

Visual language implementation through standard compiler-compiler techniques

We present a technique for implementing visual language compilers through standard compiler generation platforms. The technique exploits eXtended Positional Grammars (XPGs, for short) for modeling the visual languages in a natural way, and uses a set of mapping rules to translate an XPG specification into a translation schema. This lets us generate visual language parsers through standard compiler-compiler techniques and tools like YACC. The generated parser accepts exactly the same set of visual sentences derivable through the application of XPG productions. The technique represents an important achievement, since it enables us to perform visual language compiler construction through standard compiler-compilers rather than specific compiler generation tools. This makes our approach particularly appealing, since compiler-compilers are widely used and rely on a well-founded theory. Moreover, the approach provides the basis for the unification of traditional textual language technologies and visual language compiler technologies.