Augusto Celentano

Compiler testing using a sentence generator

A system for assisting in the testing phase of compilers is described. The definition of the language to be compiled drives an automatic sentence generator. The language is described by an extended BNF grammar which can be augmented by actions to ensure contextual congruence, e.g. between definition and use of identifiers. For deep control of the structure of the produced sample the grammar can be described by step‐wise refinements: the generator is iteratively applied to each level of refinement, producing at last compilable, complete programs. The implementation is described and some experimental results are reported concerning PLZ, MINIPL and some other languages.

Adaptation in Context-Aware Pervasive Information Systems: The SECAS Project

Purpose – The simple environment for context aware systems (SECAS) Project deals with the adaptation of applications to the context (user preferences and environment, terminal, etc.). The authors aim to develop a platform which makes the services, data and the user interface of applications adaptable to different context situations.Design/methodology/approach – Previous research has concentrated on how to capture context data and how to carry it to the application. The present work focuses on the impact of context on the application core. A case study in the medical field is also analysed.Findings – The paper illustrates a new definition of the context which separates the application data from the parameters of the context. This definition helps to establish a complete study on how to adapt applications on their three dimensions (services, content and presentation) to the context.Originality/value – The paper presents the SECAS platform, one that ensures the deployment of adaptive context‐aware applications.

Feature integration and relevance feedback analysis in image similarity evaluation

In this article we describe the results of a study on simi- larity evaluation in image retrieval using color, object orientation, and relative position as content features, in a framework oriented to image repositories where the semantics of stored images are limited to a specific domain. The focus is not on a complete description of image content, which is supposed to be known to some extent, but on the extraction of simple and immediate features that can assure, through their combination, automated image analysis and efficient retrieval. Relevance feedback is introduced as an effective way to improve retrieval accuracy. A simple prototype system is also intro- duced that computes feature descriptors and allows users to enter queries, browse the retrieved images, and refine the results through relevance feedback analysis.

Knowledge-based document retrieval in office environments: the Kabiria system

In the office environment, the retrieval of documents is performed using the concepts contained in the documents, information about the procedural context where the documents are used, and information about the regulations and laws that discipline the life of documents within a given application domain. To fulfill the requirements of such a sophisticated retrieval, we propose a document retrieval model and system based on the representation of knowledge describing the semantic contents of documents, the way in which the documents are managed by procedures and by people in the office, and the application domain where the office operates. The article describes the knowledge representation issues needed for the document retrieval system and presents a document retrieval model that captures these issues. The effectiveness of the approach is illustrated by describing a system, named Kabiria, built on top of such model. The article describes the querying and browsing environments, and the architecture of the system.In the office environment, the retrieval of documents is performed using the concepts contained in the documents, information about the procedural context where the documents are used, and information about the regulations and laws that discipline the life of documents within a given application domain. To fulfill the requirements of such a sophisticated retrieval, we propose a document retrieval model and system based on the representation of knowledge describing the semantic contents of documents, the way in which the documents are managed by procedures and by people in the office, and the application domain where the office operates. The article describes the knowledge representation issues needed for the document retrieval system and presents a document retrieval model that captures these issues. The effectiveness of the approach is illustrated by describing a system, named Kabiria , built on top of such model. The article describes the querying and browsing environments, and the architecture of the system.

Observing and adapting user behavior in navigational 3D interfaces

In a navigation-oriented interaction paradigm, such as desktop, mixed and augmented virtual reality, recognizing the user needs is a valuable improvement, provided that the system is able to correctly anticipate the user actions. Methodologies for adapting both navigation and content allow the user to interact with a customized version of the 3D world, lessening the cognitive load needed for accomplishing tasks such as finding places and objects, and acting on virtual devices.This work discusses adaptivity of interaction in 3D environments, obtained through the coordinated use of three approaches: structured design of the interaction space, distinction between a base world layer and an interactive experience layer, and user monitoring in order to infer interaction patterns. Identification of such recurring patterns is used for anticipating users actions in approaching places and objects of each experience class. An agent based architecture is proposed, and a simple application related to consumer e-business is analyzed.

Incremental LR parsers

SummaryThe concept of incremental parsing is briefly introduced. An algorithm which augments an LR parser with the capability of reanalyzing a limited part of a modified program is illustrated. The algorithm operates on a sequence of configurations representing the parse of the old input and finds the smallest part of the sequence which must be recomputed to obtain the parse of the new input.The implementation is discussed: a suitable data structure and a version of the algorithm which operates upon it are introduced; finally the problem of realizing efficient incremental parsers is faced, showing a modification to the basic algorithm which enable the reanalysis to be performed in linear time.

FFT-based technique for image-signature generation

In this paper we address image retrieval by similarity in multimedia databases. We discuss the generation and use of signatures computed from image content. The proposed technique is not based on image annotation, therefore it does not require human assistance. Signatures abstract the directionality of image objects. They are computed from the image Fourier transform, and the influence of computation parameters on signature effectiveness is discussed. Retrieval is based on spectrum comparison between a reference image, assumed as the query, and the images in a collection. We introduce a metric for comparing the spectra and ranking the result, and approach the issue of partial query specification. Sample results on a small test collection are given.

Template-Based Generation of Multimedia Presentations

Data-centered approaches to multimedia presentation design and implementation can be developed by extending methodologies and technologies common in text-based applications. A multimedia report is a multimedia presentation built on a set of data returned by one or more queries to multimedia repositories, integrated according to a template with appropriate spatial layout and temporal synchronization, and coherently delivered to a user for browsing. We discuss the problem of defining templates for such multimedia reports with a focus on media coordination and synchronization. Multimedia presentations can be automatically generated according to the template by instantiating it on actual data instances. An XML language describes the spatial layout and the temporal constraints of the media objects. An authoring system and a player have been implemented.

Schema modelling for automatic generation of multimedia presentations

Multimedia documents are an effective way to present different kinds of information, since the integration of different media types gives more expressive power and opportunities to catch the user attention. A multimedia report is a multimedia presentation built on a set of data returned by one or more queries to multimedia repositories, integrated according to a schema with appropriate spatial layout and temporal synchronization, and coherently delivered to a user for browsing. We discuss the problem of defining schemas for such multimedia reports with a focus on the media coordination and synchronization constraints. Multimedia presentations can then be automatically generated according to the schema. We have defined an XML language to describe the spatial layout and the temporal constraints of the media objects, together with a visual authoring system helping the user to design the presentation template.

A synchronization model for hypermedia documents navigation

This paper presents a model for describing the synchronization between several media delivered over a network in a Web-based environment. Synchronization concerns the download and the activation of coordinated media files according to the structure of the whole hypermedia document, the playback status of the media objects, and the user interaction. The model defines five synchronization primitives some of which can be automatically deducted from the document structure and the media-related events. The model is oriented to describe applications based on a main video or audio narration to which static or dynamic documents are attached. The model is suited for applications like distance education, professional training, Web advertising and selling, and news-on-demand.