Giuseppe Santucci

QBD*: a graphical query language with recursion

A system to query databases using diagrams as a standard user interface is proposed. The system, called Query by Diagram* (QBD*), makes use of a conceptual data model, a query language on this model, and a graphical user interface. The conceptual model is the entity-relationship model. The query language, whose expressive power allows recursive queries, supports visual interaction. The main characteristics of the interface are ease of use and the availability of a rich set of primitives for schema selection and query formulation. The expressive power of QBD* and G/sup +/, which are the only languages allowing recursive queries to be expressed graphically are compared. >

An ontology based visual tool for query formulation support

In this paper we describe the principles of the design and development of an intelligent query interface, done in the context of the SEWASIE (SEmantic Webs and AgentS in Integrated Economies) European IST project. The SEWASIE project aims at enabling a uniform access to heterogeneous data sources through an integrated ontology. The query interface is meant to support a user in formulating a precise query - which best captures her/his information needs - even in the case of complete ignorance of the vocabulary of the underlying information system holding the data. The intelligence of the interface is driven by an ontology describing the domain of the data in the information system. The final purpose of the tool is to generate a conjunctive query ready to be executed by some evaluation engine associated to the information system.

Appropriating and assessing heuristics for mobile computing

Mobile computing presents formidable challenges not only to the design of applications but also to each and every phase of the systems lifecycle. In particular, the HCI community is still struggling with the challenges that mobile computing poses to evaluation. Expert-based evaluation techniques are well known and they do enable a relatively quick and easy evaluation. Heuristic evaluation, in particular, has been widely applied and investigated, most likely due to its efficiency in detecting most of usability flaws at front of a rather limited investment of time and human resources in the evaluation. However, the capacity of expert-based techniques to capture contextual factors in mobile computing is a major concern. In this paper, we report an effort for realizing usability heuristics appropriate for mobile computing. The effort intends to capture contextual requirements while still drawing from the inexpensive and flexible nature of heuristic-based techniques. This work has been carried out in the context of a research project task geared toward developing a heuristic-based evaluation methodology for mobile computing. This paper describes the methodology that we adopted toward realizing mobile heuristics. It also reports a study that we carried out in order to assess the relevance of the realized mobile heuristics by comparing their performance with that of the standard/traditional usability heuristics. The study yielded positive results in terms of the number of usability flaws identified and the severity ranking assigned.

Structuring primitives for a dictionary of entity relationship data schemas

The data dictionary contains the description of all types of data produced, managed, exchanged, and maintained in an organization. Data descriptions (very often hundreds of schemas) should be organized in such a way to allow all the users of the information system to understand the meaning of data and their relationships. To this end, a set of structuring primitives for a dictionary of entity relationship data schemas is presented. The formal properties of such structuring primitives are investigated, and the feasibility of their usage is shown by providing a methodology for dictionary design. >

Fundamental graphical primitives for visual query languages

Abstract The need of a friendly man-machine interaction is becoming crucial for a large variety of applications. In order to reach such a friendliness a new class of languages has been proposed (Visual Languages), based on the extensive use of graphical and iconic mechanisms. We are interested in a particular subclass of Visual Languages, called Visual Query Languages (VQLs), devoted to the extraction of information from databases. VQLs are mainly based on the idea of applying new interaction mechanisms, based on the “direct manipulation” paradigm, on visually represented databases. Various VQLs have been proposed, but only a few of them are provided with a formal definition and, also when such a formal definition exists, it does not give the semantics of the graphical operations performed by the user. In this paper we aim to provide such a semantics by proposing a graphical data model, the graph model, in which the visual representation is part of the model itself and a minimal set of Graphical Primitives, in terms of which general query operations may be visually expressed. Moreover, we show that: 1. (a) such a model may be used as a general visual representation for the most common data models; 2. (b)the Graphical Primitives have the same expressive power as well-known query languages; 3. (c) the graph model and the Graphical Primitives may be used as basic constituents of more complex existing visual representations and visual query languages, thus giving them a semantics independent from the underlying data model.

A unified methodology for the evaluation of accessibility and usability of mobile applications

This article reports a unified methodology developed to evaluate the accessibility and usability of mobile computing applications, which is intended to guarantee universal access as far as possible. As a basis for the methodology, this paper presents an analysis of the accessibility guidelines, conducted to take into account the specificity of mobile systems, as well as a set of usability heuristics, specifically devised for mobile computing. Finally, it presents the results of the application of the proposed methodology to applications that have been semi-automatically developed by the MAIS Designer, a new design tool that provides applications suited to different mobile devices.

Solving Problems with Visual Analytics

Visual analytics is an emerging research discipline aiming at making the best possible use of huge information loads in a wide variety of applications by appropriately combining the strengths of intelligent automatic data analysis with the visual perception and analysis capabilities of the human user. The major goal of visual analytics is the integration of these disciplines into visual analytics to acquire well-established and agreed upon concepts and theories, combining scientific breakthroughs in a single discipline to have a potential impact on visual analytics and vice versa. In a session at FET’11, the leaders of the thematic working groups of the recently finalised FET Open coordination action VisMaster CA presented the scientific challenges that were identified in the visual analytics research roadmap, and the connection between the various disciplines and the broader vision of visual analytics. This article contains excerpts from this research roadmap to motivate further research in this direction within FET.

Query by diagram: A fully visual query system

The need of a friendly man-machine interaction is becoming crucial for a large variety of applications, in particular, those requiring frequent extraction of information from the database. Experience suggests that traditional query languages are not friendly enough for the causal user: s/he is requested to formulate queries in a textural language, without any iconic or spatial clues to help the querying process. A new generation of languages (visual languages) has been recently investigated, that attempts to make extensive use of the persons instincts and senses. In this paper we propose a fully visual system, called Query by Diagram^* (QBD^*), which is based on a conceptual data model, a query language defined on this model and a graphical user interface. The main characteristics of the interface are the ease of use, and the availability of a rich set of primitives for both schema selection and query formulation. Unlike many present proposals of graphical query systems, graphical operations are formally defined from both a syntactic and a semantic point of view.

Give chance a chance: modeling density to enhance scatter plot quality through random data sampling

The problem of visualizing huge amounts of data is well known in information visualization. Dealing with a large number of items forces almost any kind of Infovis technique to reveal its limits in terms of expressivity and scalability. In this paper we focus on 2D scatter plots, proposing a ‘feature preservation’ approach, based on the idea of modeling the visualization in a virtual space in order to analyze its features (e.g., absolute density, relative density, etc.). In this way we provide a formal framework to measure the visual overlapping, obtaining precise quality metrics about the visualization degradation and devising automatic sampling strategies able to improve the overall image quality. Metrics and algorithms have been improved through suitable user studies.

Query representation and management in a multiparadigmatic visual query environment

We propose a framework for database querying providing the user with several interaction paradigms based on different (i.e., form-based, diagrammatic, iconic, and hybrid) visual representations of the database. A unified model, namely the Graph Model, is used as the common underlying model, in terms of which databases expressed in the most common data models can be easily converted. Graph Model databases can be queried by means of the multiparadigmatic interface. The semantics of the query operations is formally defined in terms of the Graphical Primitives. Such a formal approach enables the query manager to maintain the same query consistently in any representation. In the proposed multiparadigmatic environment, the user can switch from one interaction paradigm to another during query formulation, so that the most suitable query representation can be found.