Giovanni Coray

A Taxonomy of Evolutionary Algorithms in Combinatorial Optimization

This paper shows how evolutionary algorithms can be described in a concise, yet comprehensive and accurate way. A classification scheme is introduced and presented in a tabular form called TEA (Table of Evolutionary Algorithms). It distinguishes between different classes of evolutionary algorithms (e.g., genetic algorithms, ant systems) by enumerating the fundamental ingredients of each of these algorithms. At the end, possible uses of the TEA are illustrated on classical evolutionary algorithms.

The Use of Automatic Alignment on Structured Multilingual Documents

Originally seen as a problem in translation of multilingual texts, the alignment of corresponding entities from two versions of a document has become a scientific research topic. In this paper, natural language processing methods are reviewed and an alignment algorithm is presented that takes into account both the linguistic features, and the structural data present in modern multilingual documents.

A Parallel Best-First B&B with Synchronization Phases

We present a new parallel best-first Branch and Bound algorithm conceived for machines with distributed memory. Based on the notion of problems having the same lower bound, the algorithm evaluates these problems in parallel, during each phase of its execution. These computationally intensive phases alternate with control phases where synchronization and information exchange between processors takes place. We propose a probabilistic model for predicting the performances of this algorithm and discuss the results obtained on a MIMD multiprocessor for the Asymmetric Non-Euclidean TSP.

A PARALLEL BEST-FIRST B&B ALGORITHM AND ITS AXIOMATIZATION

We present a new parallel best-first Branch and Bound algorithm designed for distributed memory machines. Starting from an axiomatization of the Branch and Bound pardigm, we develop the notion of fringes in the Branch and Bound tree which correspond to sets of equivalent problems. The algorithm proposed in this paper evaluates these sets of problems in parallel, during each phase of its execution. These computationally intensive phases alternate with control phases where synchronization and information exchange between processors lakes place. We use a probabilistic model for predicting the performances of this algorithm. Finally, we discuss the performances obtained on MIMD-DM multiprocessors for the asymmetric non-Euclidean Traveling Salesman Problem.

Designing virtual hypertexts with aggregates

This paper presents a new approach based on an extensive use of aggregate structures in hypertexts. We show an original method that induces automatically dynamic aggregates from an unstructured set of nodes. Structures of lists, graphs, trees, partitions and hypergraphs can be generated depending on the properties of the generic relations used among a set of nodes.

L'alignement des documents médiévaux

Le but de l’alignement des textes est la mise en correspondance des sous-parties similaires de deux ou plusieurs traductions ou versions d’un meme ecrit. La plupart des methodes utilisees dans la technique d’alignement reposent sur l’analyse statistique des frequences de mots ou de caracteres, ou sur la cooccurrence des chaines que ceux-ci constituent. Afin d’en ameliorer l’efficacite, d’autres approches incluent certaines proprietes linguistiques (morpho-syntaxiques et lexico-semantiques) et structurelles (marques de chapitres, de sections, etc.) des documents. Cet article expose les resultats d’une adaptation de la technique d’alignement aux etats paralleles des anciens textes a partir d’une approche multicritere qui tient compte de la similitude au niveau lexical, morpho-syntaxique et lexico-semantique du francais de la periode medievale.

Visual querying for digital libraries using dynamic hypertext aggregates: the DH31CI prototype

In the last few years, digital libraries have received a lot of attention given a maturation of recent technological achievements, particularly in the case of wide-spread computer networks, high-capacity storage media and more powerful personal computers [I]. Nevertheless, user needs must often be expressed through cryptic command languages that are still difficult to learn and to master. Documents relevant to the query are usually presented as a fiat list of titles that can be called by the user.