GuillaumeDucoffePostdoctoral Candidate

Inria Sophia Antipolis Méditerranée,2004 route des Lucioles, 06902 Sophia Antipolis

FranceH +33 (0) 637 794 319

+33 (0) 492 387 599B guillaume.ducoffe@inria.fr

Í www-sop.inria.fr/members/Guillaume.Ducoffe/

Research InterestsComputation in Large Graphs, Information-propagation in real-life graphs, Online targeting detection,Graph Theory, Combinatorics.

PHD thesis (Sep. 2014 – Dec. 2016)

title On the metric properties of large graphssupervisors David Coudertdescription Graph algorithms are the cornerstone of various problems in telecommu-

nications, social networks, bioinformatics and economics, to name a few.However, most textbook algorithms do not scale to real-life graphs withtens of thousands of nodes and billions of edges. A main objective of thethesis is to establish a finer-grained complexity of the computation ofsome graph properties and graph primitives on large graphs. It has anemphasis on the computation of hyperbolicity, and other distance-relatedgraph parameters, that all found applications in the study of geometricalrouting schemes in networks.

Education2012–2013 Parisian Master of Research in Computer Science, École Normale

Supérieure de Cachan, Cachan.top of my class

2010–2013 Master’s Degree in Engineering — Cryptography, System, Secu-rity & Networks, École Polytechnique Universitaire de Nice - SophiaAntipolis, Sophia Antipolis.top of my class

Research ExperienceDec. 2015 Research Visit, Universidad Adolfo Ibáñez / Universidad de Chile, San-

tiago de Chile.hosted by Karol Suchan.Design and implementation of graph algorithms in order to improve the trans-portation network in Santiago.

Nov.– Dec. 2014 Research Visit, Universidad Adolfo Ibáñez / Universidad de Chile, San-tiago de Chile.hosted by Karol Suchan.Study on new relations between the structure of a graph and its metric properties(properties of its distance distribution).

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Mar–Jul 2014 Research Internship: Security and Information Sharing in SocialNetworks, Columbia University, New York.supervised by Augustin Chaintreau and Roxana Geambasu.Design and theoretical limitations of learning algorithms for the problem ofOnline Targeting.

Oct–Mar 2014 Research Internship: Algorithmic Applications of the Metric Struc-ture of a Graph, Inria Sophia Antipolis Méditerranée, Nice.supervised by David CoudertStudy on relations between the diameter of a graph and other metric parameterssuch as hyperbolicity.

Mar–Aug 2013 Research Internship: Approximation Algorithms for computing inlarge graphs, Inria Sophia Antipolis Méditerranée, Nice.supervised by David CoudertFeasible computation of hyperbolicity on large graphs (a parameter related tothe stretch of geometrical routing schemes).

Jun–Sep 2012 Research Internship: Dynamics in Social Networks, Columbia Uni-versity, New York.supervised by Augustin Chaintreau and Dorian MazauricProofs of the existence of equilibria, and bounds on the time of convergence toone, in a game-theoretic model for social communities.

Jun–Aug 2011 Research Internship: Eulerian and Hamiltonian Directed Hyper-graphs, Inria Sophia Antipolis Méditerranée, Nice.supervised by Jean-Claude Bermond and Julio AraujoGeneralization of known results about Eulerian and Hamiltonian digraphs to thedirected hypergraphs.

Teaching ExperienceCo-supervision of internships 2 PFE (End of Study Project, one month each); 1 research internship

(six months) co-supervised with Frédéric Giroire.Algorithmic courses recursive programming, dichotomy, sorting algorithms, basics on Hoare

logic, etc . . . (L2 level, ∼ 30 h., École Polytechnique Universitaire deNice Sophia-Antipolis)

Programming courses Java (L2 level, ∼ 30 h., École Polytechnique Universitaire de Nice Sophia-Antipolis) and Python (L1 level, ∼ 20 h., École Polytechnique Universi-taire de Nice Sophia-Antipolis)

Web courses basics of HTML, CSS and client/server paradigm (L2 level, ∼ 30 h.,École Polytechnique Universitaire de Nice Sophia-Antipolis)

Awards and DistinctionsBest Student Paper Award [9], 15èmes Rencontres Francophones des Aspects Algorithmiques des

Télécommunications3rd Heidelberg Laureate Forum selected as a participant by an international scientific panel

Selected ProjectsFeb.–May 2012 OpenCV software for translating Sign language from a WebCam (super-

vised by Frédéric Precioso)Jan. 2012 Web developers toolkit based on the XSLT language (supervised by Paul

Franchi)

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Feb.–May 2011 DEVINT Project: Java game for visually deficient people (supervised byJ.-P. Stromboni)

LanguagesFrench mother tongueEnglish full professional working proficiency TOEIC score 900/990Italian professional working proficiency B1 level

Romanian beginner

Computer skillsGraph Theory Algorithms on Large Graphs, Fine-grained lower-bounds on graph prob-

lems, graph decompositions, metric graph invariantsTheoretical Computer Science Algorithms, Complexity, Distributed Complexity, Learning Theory, Com-

putability, Combinatorics, Graphs and Networks, Formal Languages,Game Theory

Programming Languages Java, C++, C#, C POSIX, Python, Assembly Language ARM, SQL,Scheme, Caml, Shell, Matlab, Scilab, Maple

Web Standards X(HT)ML, XSD/DTD, XSLT, XUL, CSS, JavaScript, Action ScriptOperating Systems Linux (Ubuntu,Fedora) and Windows

Softwares Astah, Cosmos, Dreamweaver, Eclipse, Editix, ESC/java, Essential Mod-eler, JProbe, Lex/Yacc, Microsoft SQL Server, Microsoft Visual Studio,NetBeans, Open Office, Understand, Valgrind

ReferencesFormer supervisors Former teachers{ David Coudert{ J.-C. Bermond{ Augustin Chaintreau{ Roxana Geambasu{ Dorian Mazauric{ Julio Araujo

{ Jean Goubault{ Paul Franchi{ Ioan Bond(more upon requests)

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Publications

Journal papers[1] D. Coudert and G. Ducoffe. “Data Center interconnection networks are not hyperbolic”. In: Journal

of Theoretical Computer Science 639.1 (2016), pp. 72–90.[2] D. Coudert and G. Ducoffe. “On the hyperbolicity of bipartite graphs and intersection graphs”. In:

Discrete Applied Mathematics (2016). To appear.[3] D. Coudert, G. Ducoffe, and N. Nisse. “To approximate treewidth, use treelength!” In: SIAM Journal

of Discrete Mathematics 30.3 (2016), p. 13.[4] J. Araujo, J-C. Bermond, and G. Ducoffe. “Eulerian and Hamiltonian dicyles in directed hypergraphs”.

In: Discrete Mathematics, Algorithms and Applications 6 (2014).[5] D. Coudert and G. Ducoffe. “Recognition of C4-free and 1/2-hyperbolic graphs”. In: SIAM Journal

of Discrete Mathematics 28.3 (2014), pp. 1601–1617.[6] G. Ducoffe. “Hamiltonicity of large generalized de Bruijn cycles”. In: Discrete Applied Mathematics

161 (2013), pp. 2200–2204.

Conference papers[1] D. Coudert and G. Ducoffe. “Liens entre symétries et étirements de routages dans les réseaux

d’interconnexion de centres de données”. In: ALGOTEL 2016 – 18èmes Rencontres Francophonessur les Aspects Algorithmiques des Télécommunications. 2016.

[2] G. Ducoffe. “The parallel complexity of coloring games”. In: SAGT 2016 – 9th International Symposiumon Algorithmic Game Theory. 2016.

[3] G. Ducoffe, N. Legay, and N. Nisse. “On the complexity of computing treebreadth”. In: IWOCA 2016– 27th International Workshop on Combinatorial Algorithms. 2016.

[4] A. Chaintreau et al. “Vers une plus grande transparence du Web”. In: ALGOTEL 2015 – 17èmesRencontres Francophones sur les Aspects Algorithmiques des Télécommunications. 2015.

[5] D. Coudert, G. Ducoffe, and N. Nisse. “Structure vs. métrique dans les graphes”. In: ALGOTEL 2015– 17èmes Rencontres Francophones sur les Aspects Algorithmiques des Télécommunications. 2015.

[6] G. Ducoffe et al. “Web’s Transparency for Complex Targeting: Algorithms, Limits and Tradeoffs”.In: SIGMETRICS ’15 Proceedings of the 2015 ACM SIGMETRICS International Conference onMeasurement and Modeling of Computer Systems. 2015.

[7] M. Lécuyer et al. “XRay: Enhancing the Web’s Transparency with Differential Correlation”. In:USENIX Security Symposium. 2014.

[8] G. Ducoffe, D. Mazauric, and A. Chaintreau. “Can Selfish Groups be Self-Enforcing?” In: Workshopon Social Computing and User Generated Content at EC’13. 2013.

[9] G. Ducoffe, D. Mazauric, and A. Chaintreau. “De la difficulté de garder ses amis (quand on a desennemis)!” In: ALGOTEL 2013 – 15èmes Rencontres Francophones sur les Aspects Algorithmiquesdes Télécommunications. 2013.

Unpublished papers[1] J. Araujo et al. “Instantaneous cycle convexity”. In preparation.[2] A. Chaintreau and G. Ducoffe. “A theory for ad targeting identification”. In preparation.[3] A. Chaintreau and G. Ducoffe. “On Web’s Transparency and an economics of online discrimination”.

In preparation.

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[4] D. Coudert et al. “Existence of a distance-preserving ordering is hard to decide”. In preparation.[5] G. Ducoffe and D. Coudert. “Clique-decomposition revisited”. Submitted.[6] G. Ducoffe, D. Mazauric, and A. Chaintreau. “The Complexity of Hedonic Coalitions under Bounded

Cooperation”. Submitted.[7] G. Ducoffe, M. Tucker, and A. Chaintreau. “Can Web’s Transparency Tools Cope with Complex

Targeting?” In preparation.[8] Cohen N. et al. “Applying clique-decomposition for computing Gromov hyperbolicity”. In preparation.

Theses[1] G. Ducoffe. “Outils Théoriques pour le Calcul Pratique de l’Hyperbolicité dans les Grands Graphes”.

MA thesis. MPRI – ENS Cachan, 2013.

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