Giuliana Vitiello

Class point: an approach for the size estimation of object-oriented systems

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.

Effort estimation modeling techniques: a case study for web applications

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.

Symbol-Relation Grammars

A common approach to the formal description of pictorial and visual languages makes use of formal grammars and rewriting mechanisms. The present paper is concerned with the formalism of Symbol?Relation Grammars (SR grammars, for short). Each sentence in an SR language is composed of a set of symbol occurrences representing visual elementary objects, which are related through a set of binary relational items. The main feature of SR grammars is the uniform way they use context-free productions to rewrite symbol occurrences as well as relation items. The clearness and uniformity of the derivation process for SR grammars allow the extension of well-established techniques of syntactic and semantic analysis to the case of SR grammars. The paper provides an accurate analysis of the derivation mechanism and the expressive power of the SR formalism. This is necessary to fully exploit the capabilities of the model. The most meaningful features of SR grammars as well as their generative power are compared with those of well-known graph grammar families. In spite of their structural simplicity, variations of SR grammars have a generative power comparable with that of expressive classes of graph grammars, such as the edNCE and the N-edNCE classes.

The Metaphor GIS Query Language

In recent years, visual representations have been increasingly used in the management of real-world phenomena as a valuable support for human?computer interaction. In the field of Geographic Information Systems, visual languages represent a promising means for allowing unskilled users to query geographic databases. In the present paper, we define the Metaphor GIS query Language (MGISQL) which allows GIS users to simultaneously capture the spatial and the thematic components of geographic data. MGISQL describes the semantic of those data in the real world and is based on a special type of visual description, the geometaphor, which is used to specify all the elements featured in a GIS domain.

A predictive parser for visual languages specified by relation grammars

We define a class of relation grammars that satisfy the context-freeness property, which is an essential condition to solve the membership problem in polynomial time. The context-freeness property is used to design a predictive parsing algorithm for such grammars. The algorithm has a polynomial time behaviour when applied to grammars which generate languages having the additional properties of connections and degree-boundedness. One remarkable result is that a polynomial time complexity is obtained without imposing (total or partial) ordering on the symbols of input sentences.<<ETX>>

Proving Properties of Logic Programs by Abstract Diagnosis

We show how declarative diagnosis techniques can be extended to cope with verification of operational properties, such as computed answers, and of abstract properties, such as types and groundness dependencies. The extension is achieved by using a simple semantic framework, based on abstract interpretation. The resulting technique (abstract diagnosis) leads to elegant bottom-up and top-down verification methods, which do not require to determine the symptoms in advance, and which are effective in the case of abstract properties described by finite domains.

A multilevel learning management system

Many authoring systems have been realized so far in order to allow users to build advanced presentation of documents. These systems represent the result of a requirement analysis performed in specific application domains and their functionality is meaningful for the domain experts. Consequently, in many cases there exists a barrier between system functionality and users, who have a limited knowledge of the domain: in order to use the application, the content expert end-user has to interact with the application expert. Such a barrier limits the effectiveness and the efficiency of the authoring system, because the development of a multimedia presentation forces the user to acquire experience far from his/her background. In this paper we introduce a new approach to educational authoring, based on a multilevel development methodology. It allows and supports teachers to create their own multimedia learning environment. The proposed approach has been experimented on an initial prototype which allows users to manage multimedia authoring of units of study.

Efficient parsing of multidimensional structures

Visual languages have motivated growing interests in the investigation of grammatical formalisms and parsing algorithms for modelling and recognizing multidimensional structures. The effectiveness of visual languages require that some efforts must be accomplished to obtain efficient parsing techniques. A general parsing scheme for relation grammars is presented. The class RG/1 of grammars is characterized which seems to be well suited for modelling visual languages of practical use. An efficient O(n log n) parsing algorithm is also given.<<ETX>>

Framy-visualising geographic data on mobile interfaces

When using a mobile device for navigating and querying a map, some visualisation and usability problems may arise due to small screens and limited interaction modes allowed by such devices. Recently, researchers have devoted their efforts to overcome these issues by introducing innovative approaches for developing advanced interfaces, capable of providing users with analytical information as well as visual summary of data. In this article, we propose a new visualisation technique, named Framy, which exploits a novel interaction metaphor for picture frames to provide hints about off-screen objects. It was conceived to cover a wider range of spatial data visualisation tasks, which may simultaneously involve different geographic layers. The technique has been embedded inside a mobile GIS application, MapGIS, designed to perform typical GIS operations and queries on mobile devices. A usability study has been performed in order to verify the benefits in efficacy, efficiency and subjective satisfaction coming from the adoption of Framy within the system.

Parsing nonlinear languages

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. >