Typing on a smartwatch presents significant challenges due to several factors, including the small size of these devices, the lack of tactile feedback, and the fat finger problem. This study presents an empirical analysis of two distinct text-entry methods for a one-line QWERTY keyboard: a traditional touch-based interaction and an input technique that leverages the rotary-crown, a feature commonly found on a substantial number of smartwatch devices. Interaction via the rotating crown enables text entry even when touch input is impractical—such as when wearing gloves, in wet conditions, or in cases of reduced precision like the ’fat finger’ problem. By rotating the rotary-crown, the user can navigate to and select the desired character, which is then input by pressing the corresponding key to confirm the selection. The method was evaluated in comparison to the touch-interaction: the results demonstrated that participants achieved higher accuracy with the rotary-crown input, with a Total Error Rate of 9%; conversely, participants exhibited faster performance with the touch-interaction, achieving a typing speed of 9.3 words per minute.

Environmental sustainability is a crucial aspect of all human activities, and recently, the field of artificial intelligence has also been required to analyze its impact in terms of energy efficiency and its relationship with accuracy. We have conducted a literature review to evaluate the sustainability of neural models, with a specific focus on neural transpilers. These models employ neural machine translation to convert source code from one programming language to another. Neural transpilers have attracted significant attention in the scientific community, with multiple studies published between 2022 and 2023 focusing on their potential integration into programmers’ development environments Our analysis focused on the environmental impact of these models, particularly in terms of electricity consumption, carbon emissions, and training time. Out of the seventeen primary studies we reviewed, nine reported information about training time and details about training devices. Our findings suggest a need for more detailed reporting on emissions and a better understanding of the carbon footprint associated with training time. This analysis sheds light on the urgency of considering the environmental costs of AI technologies and the importance of developing sustainable practices within the field.

Abstract The purpose of this paper is to assess the effects that the COVID-19 pandemic caused in the human–computer interaction (HCI) research field. Specifically, we aim to investigate how the HCI empirical research methodology changed due to the restrictions caused by COVID-19. For this reason, we analyzed all the papers published in the 2021 edition of The ACM Conference on Human Factors in Computing Systems (CHI 2021), which is generally considered the premier international conference for the field of HCI. Through the analysis of CHI papers, we identified four main effects of the COVID-19 pandemic on HCI research: influence on participants; influence on apparatus; influence on experiment procedure; other influences. These effects are described in detail and broken down into additional subcategories. Moreover, papers on pandemic-related topics were also identified. In addition, we performed some comparisons with the previous and successive edition of the conference, and extended some analysis, e.g categorization, to CHI 2022 papers. The analysis found that 23% of CHI 2021 papers and 36% of CHI 2022 papers reported some influences of the pandemic, the most common being a change in the procedures researchers used to interact with participants in their studies, in most cases based on remote communication technologies.

We present a technique that aims to make text editing on smartphones more efficient. One of the main difficulties of editing on smartphones is the cursor positioning since the characters are usually smaller than the user finger, and for this reason a number of editing techniques have been proposed. Our technique is primarily designed to help the user position the cursor in the desired location: after the user has tapped on the text to position the cursor, soft keys with directional arrows appear on the screen and allow the user to move the cursor by tapping on them. Moreover, in addition to cursor placement, the technique also allows to perform the main editing operations through additional dedicated buttons for select/cut/copy/paste.

Abstract In this paper, we present ParVis, an interactive visual system for the animated visualization of logged parser trace executions. The system allows a parser implementer to create a visualizer for generated parsers by simply defining a JavaScript module that maps each logged parser instruction into a set of events driving the visual system interface. The result is a set of interacting graphical/text windows that allows users to explore logged parser executions and helps them to have a complete understanding of how the parser behaves during its execution on a given input. We used our system to visualize the behavior of textual as well as visual parsers and describe here two of these uses. Moreover, in order to validate the efficacy of our system, we ran a user experiment where students analyzed a CUP-generated parser both with ParVis, instantiated to LALR parsers, and the standard CUP debug facilities. The results show that students can indeed analyze parser behavior and find mistakes in parser specifications more easily and quickly using ParVis. In particular, in some parser design tasks, using ParVis participants achieved a higher success rate of 50% in 42% less time with respect to the baseline system.

Abstract In this article, we present PolyRec Gesture Design Tool (PolyRec GDT), a tool that allows the definition of gesture sets for mobile applications. It supports the entire process of designing gesture sets, from collecting gestures to analyzing and exporting the set created for use in a mobile application. It is equipped with the PolyRec gesture recognizer, a unistroke recognizer based on template matching with good accuracy and performances while still allowing support for other recognizers. The main features of PolyRec GDT include the ability to collect gestures directly on mobile devices, to detect similarities between gestures to help the designer to detect ambiguities in the design phase, and the ability to automatically select the most representative gestures for each gesture class by using a clustering technique to increase recognition speed without affecting accuracy. Experimental results show that this latter feature allows an increase in accuracy compared with when the same operation is performed manually by developers or randomly by software. Finally, a user study was carried out to evaluate PolyRec GDT, in which participants were asked to use it to add gesture functionality to a mobile application. The results showed that with the support of PolyRec GDT this operation took only a few minutes for participants with mobile development experience, whereas it would have taken much longer without the support of PolyRec GDT.

In this paper, we present Domus, an educational game for multi-touch tables that makes use of a Tangible User Interface (TUI). In particular, it uses as game pieces physical objects called tangibles, which have conductive feet arranged in different patterns so that the device can recognize their position/rotation.

In this paper, we present ParVis, an interactive visual system for the animated visualization of logged parser trace executions. The system allows a parser implementer to create a visualizer for generated parsers by simply defining a JavaScript module that maps each logged parser instruction into a set of events driving the visual system interface. The result is a set of interacting graphical/text windows that allows users to explore logged parser executions and helps them to have a complete understanding of how the parser behaves during its execution on a given input.

Generalized parsers for visual languages result to be more complex than the corresponding text parsers: their applications to ambiguous inputs with visual tokens scattered and/or connected on a 2d or 3d space are very difficult to trace without the support of proper visualization tools. In this work, we give a brief description of generalized parsers for visual structures and illustrate a tool for the visualization of its execution. To do this, we provide examples based on a Visual Generalized LR (VGLR) parser applied to flowcharts.

We present the design and the evaluation of a soft keyboard aimed at facilitating the input of programming code on mobile devices equipped with touch screens, such as tablets and smartphones. Besides the traditional tap on a key interaction, the keyboard allows the user to draw gestures on top of it. The gestures correspond to shortcuts to enter programming statements/constructs or to activate specific keyboard sub-layouts. The keyboard was compared in a user study to a traditional soft keyboard with a QWERTY layout and to another state-of-art keyboard designed for programming. The results show a significant advantage for our design in terms of speed and gesture per characters.

The results of an experimental study on handwriting on smartwatches are described in this study. This study aims to gain knowledge on the current practice and possible future developments on smartwatches. This includes two experiments: the first experiment aims to compare a state-of-the-art commercial handwriting system to other competing text entry methods based on soft keyboards, whereas the other experiment allows us to gather some useful information regarding users' performance and preference in an ideal setting (without character recognition), so as to direct the design of future handwriting applications on small devices. In the first experiment, we obtained an initial entry speed of 7.5 wpm, lower than that of the other compared methods. The performance obtained in the second experiment, in the range of 15-19 wpm, suggests that by appropriately changing some settings (e.g., improved recognition and feedback, preferred writing style, and spare of space characters), the entry speed can be significantly increased. The results also showed that users prefer to enter uppercase characters and that, although this style of writing requires a significantly greater number of gestures per character, it does not adversely affect the writing speed.

We present a software system aimed at providing support to the management of processes for the self evaluation of the quality of degree programmes. The system was developed for quality management at the University of Salerno, Italy. Its main functionalities include: monitoring of the process status, scheduling of meetings, document management, support for working groups. With the help of some screenshots, the main features will be described in the context of scenarios that commonly arise in the management of processes of self-assessment of quality.

We present a novel gesture recognizer suitable for fast prototyping of gesture-based applications. The recognizer uses a nearest neighbor approach, and requires a small number of samples for each class. The similarity between two gestures is calculated through a three steps procedure: firstly, each gesture is approximated to a polyline, in order to extract its main movements; then, the two polylines are aligned to obtain an equal number of segments from both of them; lastly, the distance is found by summing the contribution of each pair of segments. We tested the recognizer on two different datasets and found that it performs more accurately than a state-of-art method.

KeyScretch is a text entry method for devices equipped with touch-screens, based on a menu-augmented soft keyboard. In these keyboards, a menu containing a small number of frequent characters is shown, while a key is pressed, allowing further character entry by menu selection. KeyScretch improves the previously studied menu-based methods by enabling the interpretation of compound strokes, which allow the input of text chunks longer than two characters. The performance of the method is analyzed on different kinds of touch-screens: First, we present a 25-session user study on a stylus-based device, showing that an instance of the method optimized for Italian can be learned in a reasonable time by the users and significantly outperforms the traditional method based on the tapping interaction. Then, we define and validate a model for predicting expert text entry rates on finger-based devices. The predicted rates for instances of KeyScretch optimized for different Western languages vary from about 44-50 words/min on the Qwerty layout, enabling improvements in the range of 30-49% as compared with the traditional method.

Auto completion has proven effective in various text-based applications. Conversely, no experiments have been carried out on the automatic completion of hand-drawn symbols and only a few systems have been presented in the literature for this purpose. Nevertheless, such a feature might be useful in different domains, e.g. for accelerating symbol retrieval and for launching complex gestural commands. In this paper we present a user study aimed at evaluating the human performance in hand-drawn symbol auto completion. In particular, using a set of more than 100 symbols belonging to the Military Course of Action domain, we evaluated the conditions under which the users are willing to exploit the auto completion functionality and those under which they can use it efficiently. As a result, we obtained that in a drawing task the auto completion functionality can be used in a profitable way, with a drawing time saving of about 18%.

In recent years there has been a growth in size and complexity of the projects managed by public or private organizations. This leads to increased probability of project failures, frequently due to the difficulty and the ability to achieve the objectives such as on-time delivery, cost containment, expected quality achievement. In particular, one of the most common causes of project failure is the very high degree of uncertainty that affects the expected performance of the project, especially when different stakeholders with divergent aims and goals are involved in the project.

Euler diagrams (EDs) are a popular means of visualizing set-based relationships. We describe the advancement of EulerSketch, based on a novel encoding of EDs. In particular, EulerSketch allows a user to sketch and interact with EDs and automatically produce a code representation for them. It also enables code storage and retrieval and permits to automatically re-draw an ED from its code representation. Some features are inspired by earlier works [4, 6, 3].

We present a code which captures the topology of closed-curve based diagrams (e.g. Euler diagrams (EDs) are used to visualize set-based relationships, whilst knot diagrams represent knotted structures), often used in visual languages. We briefly indicate how to construct a diagram from such a code. Furthermore, we present an interactive software artefact with a human-centric focus, permitting users the freedom to construct and transform diagrams at either the diagram or the code level, implementing algorithmic procedures developed.

The simulation of dynamic systems in aeronautic applications is usually accomplished by integrating different software components that model different aspects of an aircraft. This paper, based on the state of the art of multi-physic systems co-simulation, describes the work in progress for the definition of a tool able to convert an electrical network architecture for an all-electric aircraft, defined in the Hardware Description Language of Synopsys SABER, into a Modelica object which is readable from a multi-physical simulation environment.

We present a video game to learn the KeyScretch text entry method. The typing game helps the users to learn the method while having fun, letting them practice on the most frequent gestures associated to text and reach an acceptable expertise level.

KeyScretch is a recently proposed text entry method which makes use of gestures to input frequent word chunks on a menu-augmented soft keyboard. Each gesture is initiated on a key and is driven by the key surrounding menu. In this paper we present the performance of an instance of the method with a 4-items menu, specifically designed for the Italian language. The study shows that the method is easy to learn and significantly outperforms the traditional tapping-based method on the QWERTY layout.

Although textual interfaces for browsing scientific papers have several drawbacks, they are still the most used in digital libraries. Several visual approaches have been proposed in recent years in order to provide the user with a deeper insight of the search context and to allow him/her to quickly gather a collection of documents judged as useful for his/her research. This paper presents CyBiS, a novel 3D analytical interface for a Bibliographic Visualization Tool with the objective of improving scientific paper search. The design choices are justified on the basis of previous experiences described in literature and its effectiveness is shown through the description of an example session.

The progress achieved in the field of computer vision and the great improvement and diffusion of mobile technologies enable the exploration of new models of human-computer interaction, especially with respect to Augmented Reality (AR) scenarios. On the other hand, the lack of rapid prototyping environments for the development and testing of new systems of AR and Mixed Reality, may slow down the process of adoption of these technologies. This document, based on the state of the art of AR technology and on particular of AR development tools, describes the work in progress for the definition of a tool for the rapid prototyping of applications using mobile devices. The scope of the tool is twofold: to simplify the business development and simulation process of specific scenarios and to provide a tool to support the analysis of the quality of human interactions in AR environments.

In the field of syntactic recognition of hand-drawn visual languages, the recognition of the relations among graphical symbols is one of the first important tasks to be accomplished and is usually reduced to recognize the attachment areas of each symbol and the relations among them. In this paper we present an approach for identifying attachment areas on sketched symbols. The approach is independent from the method used to recognize symbols and assumes that the symbol has already been recognized. The approach is evaluated through a user study aimed at comparing the attachment areas detected by the system to those devised by the users. The results show that the system can identify attachment areas with a reasonable accuracy.

In this paper we present a visual system for the analysis of user behaviour during the execution of Web tasks based on visual data mining techniques. In particular, our system presents a suite of charts providing views of user behaviour starting from the well known clickstream visualization down to single user page interaction visualizations. The navigation through the views is enabled through ad-hoc defined zoom and filter operations. We give an overview of the architecture of the prototypical system and, in order to demonstrate the effectiveness of the approach and to give the reader an insight of the possible analysis types, we present a comparative analysis of an usability test performed on the two popular Web sites for booking flights.

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.

Sketching is considered as a way to naturally express ideas during the early phases of design. For this reason, many efforts have been made to develop user interfaces and recognizers, which enable users to create sketches using pen-based devices. However, in some domains, such as in architectural and engineering fields, the drawing process turns out to be particularly tedious and time-consuming, since the symbols to be drawn may have a complex shape and recur many times in the sketches. In this paper we present a technique for symbol completion that allows users to rapidly draw diagrammatic sketches. The completion technique recovers the information on missing strokes by interacting with symbol recognizers, which are automatically generated from grammar specifications. Moreover, in order to maintain the sketch layout more familiar to the users, the added strokes are drawn according to the user drawing style.

The term computer managed instruction (CMI) often refers to a set of functionalities which allow learning objects to be launched in the learning management system and to exchange data with it. A framework for the support of CMI functionalities in learning management systems, named CMIFramework, has been developed at the University of Salerno. In this paper, we present two case studies concerning the adoption of CMI functionalities, using CMIFramework, in different e-learning contexts. Our present work is aimed at demonstrating the ease in using the framework and its power in solving several problems connected to the adoption of CMI functionalities

The correlation between the effort to develop a learning process and early size measures could be used to assess the usability of an employed tool. In particular, when the measures are obtained from the learning process specification and they are relevant effort indicators we can assert that the technical competences of instructional designers are not relevant for the tool usage. We present initial results of applying empirical analysis to confirm a previously usability study performed on the ASCLO-S (Adaptive Self consistent Learning Object SET) editor, a visual language based tool for developing adaptive learning processes.

Standardization efforts in e-learning are aimed at achieving interoperability among Learning Management Systems (LMSs) and Learning Object (LO) authoring tools. Some of the specifications produced have reached quite a good maturity level and have been adopted in software systems. Some others, such as SCORM Run-Time Environment (RTE), have not reached the same success, probably due to their intrinsic difficulty in being understood adequately and implemented properly. The SCORM RTE defines a set of functionalities which allow LOs to be launched in the LMS and to exchange data with it. Its adoption is crucial in the achievement of full interoperability among LMSs and LO authoring tools. In order to boost the adoption of SCORM RTE in LMSs, we propose a Service Oriented Architecture (SOA)-based reference model for offering the SCORM RTE functionalities as a service, external to the LMS. By externalizing functionalities from LMSs, our model encourages the independent development of e-learning system components, allowing e-learning software producers to gain several benefits, such as better software re-use and easier integration and complexity management, with a consequent cost reduction. The proposed model is validated through a prototype system, in which a popular LMS, developed with PHP language, is enhanced with the support of SCORM RTE functionalities, provided by an external Web service based on Java technology.

A reliable effort estimation is crucial for a successful web application development planning. Several approaches exist to address this issue. Among them, the algorithmic approach is one of the most widely used and investigated methods. It is based on suitable effort prediction models which relate the development effort with project characteristics. The size represents one of the most interesting characteristics of software products and several measures can be defined in order to estimate the size of web systems. Moreover, several techniques have been proposed in the literature to build the effort prediction models. Thus, of special interest should be to establish the most effective size measures to be employed in effort prediction models and the most suitable techniques for the model construction. To this aim some empirical studies have been undertaken so far. Since it is widely recognized that several investigations should be performed to verify/confirm empirical results, in the paper we will report on an empirical analysis we have carried out by exploiting data coming from 15 web projects developed by a software company. In particular, for the analysis we have considered two sets of size measures: Length Measures (e.g. number of pages, number of medias, number of client and server side scripts) and Functional Measures (e.g. external input, external output, external query). Moreover, we have employed different techniques, such as Linear Regression, Regression Tree, and Analogy-Based Estimation, in order to determine the one that provides the best prediction.

Parsing hand-drawn diagrams is a definitely complex recognition problem. The input drawings are often intrinsically ambiguous, and require context to be interpreted in a correct way. Many existing sketch recognition systems avoid this problem by recognizing single segments or simple geometric shapes in a stroke. However, for a recognition system to be effective and precise, context must be exploited, and both the simplifications on the sketch features, and the constraints under which recognition may take place, must be reduced to the minimum. In this paper we present an agent-based framework for context-driven interpretation of symbols in diagrammatic sketches that heavily exploits contextual information for ambiguity resolution. Agents manage the activity of low-level hand-drawn symbol recognizers, that may be heterogeneous for better adapting to the characteristics of each symbol to be recognized, and coordinate themselves in order to exchange contextual information, thus leading to an efficient and precise interpretation of sketches

The existing sketch recognizers perform only a limited drawing recognition since they process simple sketches, or rely on drawing style assumptions that reduce the recognition complexity, and in most cases they require a substantial amount of training data. In this paper we present a parsing strategy for the recognition of hand-drawn diagrams that can be used in interactive sketch interfaces. The approach is based on grammar formalism, namely sketch grammars (SkGs), for describing both the symbols' shape and the syntax of diagrammatic notations, and from which recognizers are automatically generated. The recognition system was evaluated in the domain of UML use case diagrams and the results highlight the recognition accuracy improvements produced by the use of context in the disambiguation process

In this paper, we propose an approach for the construction of meta-CASE workbenches, which suitably integrates the technology of visual language generation systems, UML metamodeling, and interoperability techniques based on the GXL (graph exchange language) format. The proposed system consists of two major components. Environments for single visual languages are generated by using the modeling language environment generator (MEG), which follows a metamodel/grammar-approach. The abstract syntax of a visual language is defined by UML class diagrams, which serve as a base for the grammar specification of the language. The workbench generator (WoG) allows designers to specify the target workbench by means of a process model given in terms of a suitable activity diagram. Starting from the supplied specification WoG generates the customized workbench by integrating the required environments.

Sketch-based user interfaces are increasingly common and are being built for a variety of different disciplines. However, at present the implementation of sketch recognizers is quite time consuming since they are mostly based on specific techniques, as opposed to several other fields such as textual/visual languages and speech recognition, which benefit from the availability of compiler generation techniques and tools. This paper proposes a grammar formalism, namely Sketch Grammars (SkGs), for describing both the shape of the symbols' language and the syntax of sketch languages. Recognizers are automatically generated from the sketch grammar descriptions.

In this paper we propose an approach for constructing sketch parsers whose recognition accuracy and speed is significantly improved by acquiring information on the user's sketching style during a training phase. The construction process consists in specifying a sketch grammar description of the language syntax, automatically generating a parser from such specification, and let the user train the recognition system on a set of sketch sentences.

In this paper, we present an FP-like approach, named class point, which was conceived to estimate the size of object-oriented products. In particular, two measures are proposed, which are theoretically validated showing that they satisfy well-known properties necessary for size measures. An initial, empirical validation is also performed, meant to assess the usefulness and effectiveness of the proposed measures to predict the development effort of object-oriented systems. Moreover, a comparative analysis is carried out, taking into account several other size measures.

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

Sensor data fusion imposes a number of novel requirements on query languages and query processing techniques. A spatial/temporal query language called /spl Sigma/QL has been proposed to support the retrieval and fusion of multimedia information from multiple sources and databases. In this paper we investigate fusion techniques, multimedia data transformations and /spl Sigma/QL query processing techniques for sensor data fusion. Fusion techniques including fusion by the merge operation, the detection of moving objects, and the incorporation of belief values, have been developed. An experimental prototype has been implemented and tested to demonstrate the feasibility of these techniques.

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.

Banking legacy systems intensively exchange messages in electronic format. Such systems are, for their nature, difficult to update and maintain. As a consequence, the introduction of new types of messages is a hard task. Adding new functionalities requires custom coding and software reuse is seen as a key to obtain a better time-to-market factor, risk and cost reduction. In this paper we describe the architecture and part of the implementation of the SI.RE. Visual System, an Interbanking Network Information System that lets us generate gateways for the exchange of electronic messages among banking legacy systems and supports software reuse. In particular, the SI.RE visual system contains a Visual Programming Environment that allows us to obtain a rapid development of the message handling functions. This environment implements a Visual Programming Language UVG that allows a programmer to reuse COBOL routines.

In this paper we present the approach based on the formalism of Extended Positional Grammars for specifying, designing and implementing visual modeling languages. In order to stress the main characteristics of the approach and highlight its power, we describe the use of the formalism to implement statecharts languages which represent one of the most complex visual modeling languages used in the software engineering field. In the paper special emphasis is put on describing the benefits deriving from the use of such formal specifications such as incrementality, easy customization, and automatic generation of visual programming environments. Such features turn out to be especially important because visual modeling languages are subjected to continuous changes as the history of statecharts languages and UML diagrams shows. Moreover, visual languages can be effectively used only if they are supported by a powerful visual environment within they are embedded and used.

We present the Component-Based Visual Environment Development (CB-VED) process for building visual language environments and introduce the Visual Language Desk (VLDesk) system supporting its implementation. The proposed approach is based on software reuse at different granularity levels and enables incremental development. The VLDesk exploits all the knowledge gained from the development of the Visual Language Compiler-Compiler tool extending its functionalities with many adjunctive features useful in the presented development process. One of the aims of this research consists of the application of software engineering techniques to the incremental development of visual language environments.

The development of desktop virtual reality cultural exhibitions on the web is a challenging process, because it requires a collection of skills, ranging from art to 3D Internet technologies, and involves a variety of tasks. The need of suited approaches able to support the development of such exhibitions has motivated the introduction of the approach proposed in the paper. Such an approach is characterized by a strong attention towards the content experts, by a clear identification of the actors involved in the development process, and by a set of visual modeling languages, which support the high-level design of the exhibition and allow a more effective communication between the heterogeneous members of the project. Such modeling languages have been embedded in an authoring system which profitably supports the main figures to carry out their tasks.

The modeling of multimedia databases in the context of multimedia information systems is a complex task. The designer has to model the structure and the dynamic behavior of multimedia objects, together with possible user interactions with them. These can include content-based queries, and dynamic presentations, which might both require the construction of special index structures on the stored data. In this paper we present a methodology for the design of multimedia databases. The methodology extends some of the Unified Modeling Language (UML) diagrams with constructs to model the structure of multimedia objects, their dynamic behavior, presentation layout, and user interactions. These constructs allow a designer to model important aspects of database oriented multimedia applications. As a consequence, it is possible to construct refinement techniques to map our high level models onto logical data models of several target multimedia DBMSs. In particular, we describe how to map our conceptual models onto extended relational data models.

In order to achieve quality products with reliable cost and effort estimations, one of the main tasks for planning software project development is size estimation. This is especially true when dealing with interactive applications which represent critical components in a software project. In the paper, we address the problem of the size estimation of interactive graphical applications developed using the object-oriented methodology. In particular, we define and validate a metric, the Class Point metric, for estimating the size of object-oriented GUIs. The method is based on the idea of quantifying classes in a program analogous to function counting performed by the function point metric. Theoretical validation has proven the consistency of the Class Point metric as size measure. Empirical validation provides evidence that the Class Point metric is a useful measure for OO software size.

The Visual Language Compiler-Compiler (VLCC) is a grammar-based graphical system for the automatic generation of visual programming environments. In this paper the theoretical and algorithmic issues of VLCC are discussed in detail. The parsing methodology we present is based on the "positional grammar" model. Positional grammars naturally extend context-free grammars by considering new relations in addition to string concatenation. Thanks to this, most of the results from LR parsing can be extended to the positional grammars inheriting the well known LR technique efficiency. In particular, we provide algorithms to implement a YACC-like tool embedded in the VLCC system for automatic compiler generation of visual languages described by positional grammars.

Introduces a variation of the 2D string representation for symbolic pictures, the non-redundant 2D string, and analyze it with respect to compactness and non-ambiguity. It results that the non-redundant 2D string is a more compact representation than the 2D string, and that the class of unambiguous pictures under the non-redundant 2D string is almost equal to the class of unambiguous pictures under the reduced 2D string, up to a special case. Moreover, we show that the compactness of the new index does not affect the time complexity of picture retrieval.>

The diagrammatic approach to user interfaces for computer-aided software development toolkits, visual query systems, and visual programming environments, is based on the use of diagrams and charts traditionally drawn on paper. In particular, the VLG system (Visual Language Generator) has been proposed to generate icon-oriented visual languages customized for given applications. The syntactical model underlying the interpretation of a visual language in VLG has been designed to describe icon-oriented visual languages. In order to enable the VLG system to apply to any kind of graphical languages, like diagrammatic ones, it is necessary to find a more general syntactical model able to support both their generation and interpretation. This paper addresses the comprehension of the features that a grammatical formalism for nonlinear languages must have to match any requirement for an efficient parsing. To this aim, relation grammars support an easy implementation of a general parsing algorithm for multidimensional languages, parametric with respect to the rewriting rules of the grammar. We compare the expressive power of relation grammars to grammatical formalisms for graph grammars.>

Several iconic indexes for representing three-dimensional scenes are presented. The approach extends previous work in iconic indexing of two-dimensional scenes in a unified manner. Good characteristics for iconic indexes are also pointed out. OPP2 and OPP3, two-dimensional iconic indexes for three-dimensional scenes, are introduced. The problem of ambiguity in the OPP2 and OPP3 representations of three-dimensional scenes is studied in detail and a class of images for which they are unambiguous is identified. The Genstring, a linear iconic index which can be used to represent two-, three-, or higher-dimensional scenes, is introduced. It provides a compact, unambiguous representation of a three-dimensional scene. The Genstring takes advantage of previous work, thus providing fast pattern matching for higher-dimensional scenes. In fact, the pattern matching algorithm given for k-dimensional scenes is as fast as that previously given for two-dimensional scenes.>