Section: Partnerships and Cooperations

International Initiatives

IFCAM Program, Applications of Graph homomorphisms

• Program: IFCAM 2018-2020 (http://math.iisc.ac.in/~ifcam/)

• Project acronym: –

• Project title: Applications of graph homomorphisms on graph database

• Duration: Janvier 2018 - Décembre 2020

• Coordinator: Reza Naserasr (for France) - Sagnik Sen (for India)

• Other partners: complete list of participants on the project website.

• Abstract: In this project, we are going to study the graph homomorphism problems from a very general point of view. Apart from studying the usual graph homomorphism on undirected graphs, we will study it for different types of graphs such as, signed graphs, oriented graphs, edge-colored graphs, colored mixed graphs etc. We will apply the theories and techniques associated with graph homomorphism to solve practical problems. Our main application oriented work is studying graph homomorphism in the context of graph database, a type of database now a days used even by popular social medias. Graph homomorphism is equivalent to the query evaluation problem in graph database, and thus have exciting intersection with the theory. In our group we have experts of graph homomorphisms as well as graph database making this project a potential case for Indo-French interdisciplinary collaboration. We want to organize a workshop by the end of this project. We also consider a few other application oriented topics as auxiliary research tracks inside this project.

Inria International Labs

Inria Chile

Associate Team involved in the International Lab:

ALDYNET

• Title: distributed ALgorithms for DYnamic NETworks

• International Partner (Institution - Laboratory - Researcher):

  • Universidad Adolfo Ibañez (Chile) - Facultad de Ingeniería y Ciencias - Karol SUCHAN

• Start year: 2016

• See also: https://team.inria.fr/coati/projects/aldynet/

• This associated team would be the natural continuation of the fruitful EA AlDyNet (2013-2015, https://team.inria.fr/coati/projects/aldynet/)

  The main goal of this Associate Team is to design and implement practical algorithms for computing graph structural properties. We will then use these algorithms on a concrete case of study which concerns the transportation network of the Santiago agglomeration. We are both interested in theoretical results concerning the feasibility of computing graph properties, and by their practical implementation (using Sagemath) for our application and their diffusion in the scientific community. There are three main objectives:

  1) Design efficient algorithms to compute important graph properties (hyperbolicity, treelength, centrality, treewidth...) in real networks. We are not only interested by the worst-case time-complexity of these algorithms but by their performance in practice.

  2) Implement and document our algorithms using the open-source framework SageMath. One advantage of using SageMath is that it has interfaces with other graph libraries (igraph, Boost...) and with Linear Programming solver (GLPK, Cplex...). Moreover, the success of SageMath (which has accumulated thousands of users over the last 10 years) will participate to the diffusion of our algorithms.

  3) Apply our algorithms on the Santiago transportation network that have been collected by our Chilean partner during the last year of AlDyNet (2013-2015). Based on the results, propose tools for decision support in designing bus routes, timetables, etc. More precisely, we have collected information about the use of public transport (data of smart cards for automatic fare collection -BIP-, bus routes and bus schedules, etc.), urban infrastructure information, schools’ addresses, and approximate locations where students live. We have started to clean and consolidate these data. We will then develop decision support tools, for example, for improving quality education accessibility.

Inria International Partners

Informal International Partners

Apart from formal collaboration Coati members maintain strong connections with the following international teams, with regular visits of both sides.

• Universidade Federal do Ceará (Fortaleza, Brazil), ParGO team;

• Universidade Estadual do Ceará (Fortaleza, Brazil), Prof. Leonardo Sampaio;

• Univ. of Southern Denmark (Odense, Denmark), Prof. Jørgen Bang-Jensen;

• RWTH Aachen Univ., Lehrstuhl II für Mathematik (Aachen, Germany), Prof. Arie M.C.A. Koster;

• Concordia Univ. (Montréal, Québec, Canada), Prof. Brigitte Jaumard.