Tianxiao Liu

TGV: a tree graph view for modeling untyped XQuery

Tree Pattern Queries [7,6] are now well admitted for modeling parts of XML Queries. Actual works only focus on a small subpart of XQuery specifications and are not well adapted for evaluation in a distributed heterogeneous environment. n nIn this paper, we propose the TGV (Tree Graph View) model for XQuery processing. The TGV model extends the Tree Pattern representation in order to make it intuitive, has support for full untyped-XQuery queries, and for optimization and evaluation. Several types of Tree Pattern are manipulated to handle all XQuery requirements. Links between Tree Patterns are called hyperlinks in order to apply transformations on results. n nThe TGV has been implemented in a mediator system called XLive.

Untyped XQuery Canonization

XQuery is a powerful language defined by the W3C to query XML documents. Its query functionalities and its expressiveness satisfy the major needs of both the database community and the text and documents community. As an inconvenient, the grammar used to define XQuery is thus very complex and leads to several equivalent query expressions for one same query. This complexity often discourages XQuery-based software developers and designers and leads to incomplete XQuery handling.

Cost Framework for a Heterogeneous Distributed Semi-structured Environment

This paper proposes a generic cost framework for query optimization in an XML-based mediation system called XLive, which integrates distributed, heterogeneous and autonomous data sources. Our approach relies on cost annotation on an XQuery logical representation called Tree Graph View (TGV). A generic cost communication language is used to give an XML-based uniform format for cost communication within the XLive system. This cost framework is suitable for various search strategies to choose the best execution plan for the sake of minimizing the execution cost.

Mario, Warcraft ou Pokemon ? La programmation de jeux vidéo comme motivation dans l'apprentissage des sciences informatiques

La programmation de jeux video est une motivation souvent donnee par les etudiants desireux de suivre une formation en sciences informatiques. Or implementer un jeu video est complexe et fait appel a beaucoup de notions dont la plus visible est lInterface Homme-Machine (IHM). Cette derniere fait souvent obstacle a la proposition dun sujet de projet portant sur le jeu video. Pourtant, les jeux video font appel aux notions fondamentales (algorith-miques, bases de donnees, reseaux, intelligence artificielle, etc.) des sciences informatiques. Nous montrons dans cet article que la plupart des jeux video peuvent neanmoins etre implementes avec une IHM minimale qui pourra ensuite etre etendue suivant la motivation des etudiants. Dans cet article, nous avons categorise les jeux existants suivant leur genre et les avons classes en fonction des competences visees tout au long de la formation informatique a luniversite de Cergy-Pontoise. Nous montrons comment nous avons mise en place des solutions pour encadrer les etudiants dans leur realisation de projets de jeux video. Les resultats sur 14 ans d’enseignements en projets de jeux video montrent leffica-cite de cette approche dans l’apprentissage des sciences informatiques.