Daisy Structure in Desarguesian Projective Planes of Order 2^n+1 Gabriela Araujo Pardo IMATE–UNAM   A Combinatorial Problem in Cyclic Abelian Groups Gyula A. Karolyi Eötvös University, Budapest (joint work with Oriol Serra and Balázs Szegedy)   What is in a Diagram? Rodolfo San Agustín Chi Universidad Nacional Autónoma de México   Spin Graphs José Seade IMATE–Cuernvaca, UNAM   Modular Hadamard Matrices Shalom Eliahou Université du Littoral Cote d’Opale, Calais   The Chip-firing Game and the Tutte Polynomial Criel Merino IMATE–UNAM   Branch Width and well-quasi-ordering in Matroids and Graphs Geofrey P. Whittle Victoria University of Wellington (joint work with Jim Geelen and Bert Gerards)   The Tutte Polynomial on the Square Lattice Pastora Revuelta-Marchena Escuela Universitaria de Arquitectura Técnica (joint work with M.E. Gegundez and A. Márquez)   Combinatorics of Mappings Jaroslav Nesetril Charles University   Algorithms for Graph Homomorphisms Pavol Hell Simon Fraser University (joint work with M. Rosenfeld)   Graph Decompositions and SONET Networks Charles J. Colbourn University of Vermont   On Some Different Aspects of Clique Graphs Jayme Luiz Szwarcfiter Universidade Federal do Rio de Janeiro   Using Complex Semidefinite Programming for Combinatorial Optimization Problems Michael Goemans Massachusetts Institute of Technology   Sequences from Finite Regular Semigroup with Group Products Jean Loyola Oesmer University of the Philippines Los Banos   New Bounds for the Crossing Number of Cartesian Products of Cycles Hector Alfonso Juarez IICO–UASLP   Medical Surveillance, Frequent Sets, and Closure Spaces Alan P. Sprague University of Alabama at Birmingham   Irreducibility of the Tutte Polynomial of a Connected Matroid Marc Noy Universitat Politecnica de Catalunya (joint work with Criel Merino and Anna de Mier)   Dominance Codes in the Square of the Hypercube Feliú Sagols CINVESTAV–IPN   Clique Behaviour of Locally Ct Graphs. Francisco Larrión IMATE–UNAM (joint work with V. Neumann–Lara and M.A. Pizaña)   The Stable Scheduling (or Ordinal Transportation) Problem Michel Balinski Laboratoire d’Econométrie, Ecole Polytechnique   Choosing Lectures with the Independent Set Problem Rafael López–Bracho UAM-Azcapotzalco (joint work with M.A. Gutiérrez–Andrade, M.P. Ortuño Sánchez and J. Ramírez Rodríguez)   Separoids: a Characterization of Linear Uniform Acyclic Oriented Matroids Ricardo Strausz IMATE–UNAM   Theconjecture cr(Cm £ Cn) = (m ¡ 2)n is true for all but finitely Many n Gelasio Salazar UASLP IICO (joint work with L. Yu. Glebsky)   On the a-invariant of the Rees Algebra of the ideal of k-products Adrián Alcántar CINVESTAV–IPN   An (8=5 + ")-approximation for minimum two-edge-connectivity augmentations of trees Guy Even Tel Aviv University (joint work with J. Feldman, G. Kortsarz and Z. Nutov   Cyclic embeddings of knots and their applications Jorge Ramirez Alfonsin University of Bonn   Graph minors and graphs on surfaces Bojan Mohar University of Ljubljana, Slovenia   Approximating small vertex-connectivity problems via Set-Covers Guy Kortsarz The Open University (joint work with Z. Nutov)   On the normality of the monomial subring of a graph and the generalized marriage problem Rafael H. Villarreal CINVESTAV–IPN   Matrices with Dominant Staircases David Romero Instituto de Matemáticas, UNAM, Cuernavaca, México and Adolfo Sánchez-Flores Banco de México   The Theta Body and Perfect Graphs F. Bruce Shepherd Research Bell–Labs.   Half integrality of postman polyhedrons Francisco Javier Zaragoza Martínez University of Waterloo   Structure of Topologically Closed Classes of Trees Neil Robertson Ohio State University   Hopf algebras and the Penrose polynomial Irasema Sarmiento CINVESTAV–IPN   Coloring the angles of an imbedded graph Isidoro Gitler CINVESTAV–IPN   On (n,k)-critical graphs and digraphs Wolfgang Mader University of Hannover   Acyclic Combinatorics in Tournaments Víctor Neumann–Lara IMATE–UNAM   Dimension of the variety of flags fixed by a nilpotent endomorphism José Martínez Bernal CINVESTAV–IPN   An Axiomatic Approach to Intercalation Gilberto Calvillo Banco de México   Semiextensions and Circuit Double Covers Enrique García Moreno Ohio State University   Spin models and Delta–Y transformations Isaías López CINVESTAV–IPN