Jacques Le Maitre

Extending xQuery with transformation operators

In this paper, we propose to extend XQuery - the XML query language - with a set of transformation operators which will produce a copy of an XML tree in which some subtrees will be inserted, replaced or deleted. These operators - very similar to the ones proposed for updating an XML document - greatly simplify the expression of some queries in making it possible to express only the modified part of a tree instead of its whole reconstruction. We compare the expressivity of XQuery extended in this way with XSLT.

Describing multistructured XML documents by means of delay nodes

Multistructured documents are documents whose structure is composed of a set of concurrent hierarchical structures. In this paper, we propose a new model of multistructured documents and we show how to translate its instances into XML using a new kind of nodes: delay nodes, which we propose to add to the XDM model on which XPath and XQuery are based. A delay node is the virtual representation, by an XQuery query, of some of the children of its parent. Interest of delay nodes to manage multistructured documents is that they allow several nodes to virtually share their children nodes. In this way, it is possible to query, with XPath or XQuery, multistructured documents described in XML as if their different structures were really concurrent. Finally, we compare our model with the GODDAGbased model and the multicolored trees (MCT) model.

BlockWeb: An IR Model for Block Structured Web Pages

BlockWeb is a model that we have developed for indexing and querying web pages according to their content as well as to their visual rendering. These pages are split up into blocks what has several advantages in terms of page indexing and querying: (i) blocks of a page most similar to a query may be returned instead of the page as a whole (ii) the importance of a block can be taken into account, as well as (iii) the permeability of the blocks to the content of neighbor blocks. In this paper, we present the BlockWeb model and show its interest for indexing images of Web pages, through an experiment performed on electronic versions of French daily newspapers. We also present the engine we have implemented for block extraction, indexing and querying according to the BlockWeb model.

Indexing and querying segmented web pages: the BlockWeb Model

We present in this paper a model for indexing and querying web pages, based on the hierarchical decomposition of pages into blocks. Splitting up a page into blocks has several advantages in terms of page design, indexing and querying such as (i) blocks of a page most similar to a query may be returned instead of the page as a whole (ii) the importance of a block can be taken into account, as well as (iii) the permeability of the blocks to neighbor blocks: a block b is said to be permeable to a block b′ in the same page if b′ content (text, image, etc.) can be (partially) inherited by b upon indexing. An engine implementing this model is described including: the transformation of web pages into blocks hierarchies, the definition of a dedicated language to express indexing rules and the storage of indexed blocks into an XML repository. The model is assessed on a dataset of electronic news, and a dataset drawn from web pages of the ImagEval campaign where it improves by 16% the mean average precision of the baseline.

Indexing by permeability in block structured web pages

We present in this paper a model that we have developed for indexing and querying web pages based on their visual rendering. In this model pages are split up into a set of visual blocks. The indexing of a block takes into account its content, its visual importance and, by permeability, the indexing of neighbors blocks. A page is modeled as a directed acyclic graph. Each node is associated with a block and labeled by the coefficient of importance of this block. Each edge is labeled by the coefficient of permeability of the target node content to the source node content. Importance and permeability coefficients cannot be manually quantified. the second part of this paper, we present an experiment consisting in learning optimal permeability coefficients by gradient descent for indexing images of a web page from the text blocks of this page. The dataset is drawn from real web pages of the train and test set of the ImagEval task2 corpus. Results demonstrate an improvement of the indexing using non uniform block permeabilities.

Controlled Hypertextual Navigation in the SgmlQL Language

Due to the growth of networks, the notion of document has evolved to the notion of hyperdocument. It is usual to fragment documents in a set of files referencing each other, distributed over a network. Manual navigation remains the most usual way to browse this graph-like structure to query documents either from a known URL or from the output of an index server. Nevertheless, it is diffcult to avoid digressions and even getting lost in the cyberspace. Moreover, it is mandatory to read each accessed document to check its reliability. We present in this paper an extension of the SgmlQL language. The purpose of this extension is to define a specific operator to express and control hypertextual navigation. Path filters are defined and can be restricted according to the structure of the path, the followed links and the traversed documents.

Indexation et interrogation de photos de presse décrites en MPEG-7 et stockées dans une base de données XML

This paper describes a user interface, built on top of a web server, dedicated to index and query a catalogue of news photos described as MPEG-7 documents stored in an XML database. This interface has been developed within the framework of a French RNTL project called “Muse” which aimed at building an XML multimedia search engine associated with an XML repository. This paper focuses on the three main features of the interface: (i) semantic and visual indexing of photos which produces a MPEG-7 document (ii) data querying : queries are captured in query forms and translated into XQuery queries sent to the XML database through a mediator, (iii) answer presentation and classification. MOTS-CLÉS : Données multimédia, Indexation, Langage de requêtes, MPEG-7, XML, XQuery.