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Introducing multilayer stream graphs and layer centralities [article]

Pimprenelle Parmentier, Tiphaine Viard, Benjamin Renoust, Jean-François Baffier
2019 arXiv   pre-print
Graphs are commonly used in mathematics to represent some relationships between items. However, as simple objects, they sometimes fail to capture all relevant aspects of real-world data. To address this problem, we generalize them and model interactions over time with multilayer structure. We build and test several centralities to assess the importance of layers of such structures. In order to showcase the relevance of this new model with centralities, we give examples on two large-scale
more » ... large-scale datasets of interactions, involving individuals and flights, and show that we are able to explain subtle behaviour patterns in both cases.
arXiv:1910.01511v1 fatcat:nv3trrltebeefejajqmp6a2w4m

Multiplex flows in citation networks

Benjamin Renoust, Vivek Claver, Jean-François Baffier
2017 Applied Network Science  
Knowledge is created and transmitted through generations, and innovation is often seen as a process generated from collective intelligence. There is rising interest in studying how innovation emerges from the blending of accumulated knowledge, and from which path an innovation mostly inherits. A citation network can be seen as a perfect example of one generative process leading to innovation. However, the impact and influence of scientific publication are always difficult to capture and
more » ... capture and measure. We offer a new take on investigating how the knowledge circulates and is transmitted, inspired by the notion of "stream of knowledge". We propose to look at this question under the lens of flows in directed acyclic graphs (DAGs). In this framework inspired by the work of Strahler, we can also account for other well known measures of influence such as the h-index. We propose then to analyze flows of influence in a citation networks as an ascending flow. From this point on, we can take a finer look at the diffusion of knowledge through the lens of a multiplex network. In this network, each citation of a specific work constitutes one layer of interaction. Within our framework, we design three measures of multiplex flows in DAGs, namely the aggregated, sum and selective flow, to better understand how citations are influenced. We conduct our experiments with the arXiv HEP-Th dataset, and find insights through the visualization of these multiplex networks.
doi:10.1007/s41109-017-0035-2 pmid:30443578 pmcid:PMC6214274 fatcat:hhzqqiymqjekvpzvrbc2hgf7ie

Flows of Knowledge in Citation Networks [chapter]

Benjamin Renoust, Vivek Claver, Jean-François Baffier
2016 Studies in Computational Intelligence  
Knowledge is created and transmitted through generation. Innovation is often seen as a generative process from collective intelligence, but how does innovation emerges from the blending of accumulated knowledge, and from which path an innovation mostly inherit? A citation network can be seen as a perfect example of a generative process leading to innovation. Inspired by the notion of "stream of knowledge", we propose to look at the question of production of knowledge under the lens of DAGs.
more » ... e lens of DAGs. Although many works look for the evaluation of publications, we propose to look for production of knowledge within a framework for analyzing DAGs. In this framework inspired by the work of Strahler, we can also account for other well known measures of influence such as the h-index. We propose then to analyze flows of influence in a citation networks as an ascending flow. We propose an efficient dynamic algorithm for integration with modern graph databases, conducting our experiment with the Arxiv HEP-TH dataset. Our results validate the use of DAG flows for citation flows and show evidence of the relevance of the h-index.
doi:10.1007/978-3-319-50901-3_13 fatcat:3lqhgzuu3zcuhitieajsidq7ry

Experimental Study of Compressed Stack Algorithms in Limited Memory Environments [article]

Jean-François Baffier and Yago Diez and Matias Korman
2017 arXiv   pre-print
A preliminary but operational version -using Julia language [11] -was presented by Baffier et al. [5] and is available as [7] under the same MIT license.  ... 
arXiv:1706.04708v1 fatcat:uktxnohlxbdshowbzb4bm6ywam

Speeding up algorithm for maximizing barrier coverage using parametric multiroute flow

Vorapong Suppakitpaisarn, Jean-François Baffier
2015 IEICE Communications Express  
Theorem 4 (Baffier, Suppakitpaisarn, Hiraishi, and Imai [9] ) Let λ be an s-t edge connectivity of the network G. The parametric multiroute flow function can be found in OðmnÞ.  ... 
doi:10.1587/comex.4.111 fatcat:jxtqtlvbhrhl5k2mxfgqrrugnq

Gap-Planar Graphs [chapter]

Sang Won Bae, Jean-Francois Baffier, Jinhee Chun, Peter Eades, Kord Eickmeyer, Luca Grilli, Seok-Hee Hong, Matias Korman, Fabrizio Montecchiani, Ignaz Rutter, Csaba D. Tóth
2018 Lecture Notes in Computer Science  
We introduce the family of k-gap-planar graphs for k ≥ 0, i.e., graphs that have a drawing in which each crossing is assigned to one of the two involved edges and each edge is assigned at most k of its crossings. This definition is motivated by applications in edge casing, as a k-gap-planar graph can be drawn crossing-free after introducing at most k local gaps per edge. We present results on the maximum density of k-gap-planar graphs, their relationship to other classes of beyond-planar
more » ... eyond-planar graphs, characterization of k-gap-planar complete graphs, and the computational complexity of recognizing kgap-planar graphs. A drawing Γ of a graph G = (V, E) is a mapping of the vertices of V to distinct points, and of the edges of E to a continuous arcs connecting their corresponding endpoints such that no edge (arc) passes through any vertex, if two edges have a common interior point in Γ, then they cross transversely at that point, and no three edges cross at the same point. For a subset E ⊆ E, the restriction of Γ to the curves representing the edges of E is denoted by Γ [E ]. A drawing Γ is planar if no two edges cross. A graph is planar if it admits a planar drawing. A planar embedding of a planar graph G is an equivalence class of topologically equivalent (i.e., isotopic) planar drawings of G. A plane graph is a planar graph with a planar embedding. A planar drawing subdivides the plane into topologically connected regions, called faces. The unbounded region is the outer face. The crossing number cr(G) of a graph G is the smallest number of edge crossings over all drawings of G. The crossing graph C(Γ) of a drawing Γ is the graph having a vertex v e for each edge e of G, and an edge (v e , v f ) if and only if edges e and f cross in Γ. The planarization Γ * of Γ is the plane graph formed from Γ by inserting a dummy vertex at each crossing, and subdividing both edges with the dummy vertex. To avoid ambiguities, we call real vertices the vertices of Γ * that are in V (i.e., that are not dummy). A class of graphs is informally called "beyond-planar" if the graphs in this family admit drawings in which the intersection patterns of the edges are characterized by some forbidden configuration (see, e.g., [33, 35, 41] ). Research on such graph classes is attracting increasing attention in graph theory, graph algorithms, graph drawing, and computational geometry, as these graphs represent a natural generalization of planar graphs, and their study can provide significant insights for the design of effective methods to visualize realworld networks. Indeed, the motivation for this line of research stems from both the interest raised by the combinatorial and geometric properties of these graphs, and experiments showing how the absence of particular edge crossing patterns has a positive impact on the readability of a graph drawing [36] . Among the investigated families of beyond-planar graphs are: k-planar graphs (see, e.g., [12, 39, 43] ), which can be drawn in the plane with at most k crossings per edge; k-quasiplanar graphs (see, e.g., [2, 3, 25]), which can drawn without k pairwise crossing edges; fan-planar graphs (see, e.g., [9, 13, 37] ), which can be drawn such that no edge crosses two independent edges; fan-crossing-free graphs [18] , which can be drawn such that no edge crosses any two edges that are adjacent to each other; planarly-connected graphs [1], which can be drawn such that each pair of crossing edges is independent and there is a crossing-free edge that connects their endpoints; RAC graphs (refer, e.g., to [20] ), which admit a straight-line (or polyline with few bends) drawing where any two crossing edges are perpendicular to each other. Eppstein et al. [24] studied several optimization problems related to edge casing, assuming the input is a graph together with a fixed drawing. In particular, the problem of minimizing the maximum number of gaps per edge in a drawing can be solved in polynomial time (see also Section 2). We also note that a similar drawing paradigm is used by partial edge drawings (PEDs), in which the central part of each edge is erased, while the two remaining stubs are required to be crossing-free (see, e.g., [16, 17] ). Let Γ be a drawing of a graph G. Recall that exactly two edges of G cross in one point p of Γ, and we say that these two edges are responsible for p. A k-gap assignment of Γ maps each crossing point of Γ to one of its two responsible edges so that each edge is assigned with at most k of its crossings; see, e.g., Fig. 1(right) . A gap of an edge is a crossing assigned to it. An edge with at least one gap is gapped, else it is gap-free. A drawing is k-gap-planar if it admits a k-gap assignment. A graph is k-gap-planar if it has a k-gap-planar drawing. Note that a graph is planar if and only if it is 0-gap-planar, and that k-gap-planarity is a monotone property: every subgraph of a k-gap-planar graph is k-gap-planar. The summation of the number of gaps over all edges in a set E ⊂ E yields the following. Property 1. Let Γ be a k-gap-planar drawing of a graph G = (V, E). For every E ⊆ E, the subdrawing Γ[E ] contains at most k · |E | crossings. In fact, the converse of Property 1 also holds, and we obtain the following stronger result. Theorem 2. Let Γ be a drawing of a graph G = (V, E). The drawing Γ is k-gap-planar if and only if for each edge set E ⊆ E the subdrawing Γ[E ] contains at most k · |E | crossings.
doi:10.1007/978-3-319-73915-1_41 fatcat:sbkzguldkvbppnqvncsjvt5bme

Learning Interpretable Error Functions for Combinatorial Optimization Problem Modeling [article]

Florian Richoux, Jean-François Baffier
2021 arXiv   pre-print
In Constraint Programming, constraints are usually represented as predicates allowing or forbidding combinations of values. However, some algorithms exploit a finer representation: error functions. Their usage comes with a price though: it makes problem modeling significantly harder. Here, we propose a method to automatically learn an error function corresponding to a constraint, given a function deciding if assignments are valid or not. This is, to the best of our knowledge, the first attempt
more » ... the first attempt to automatically learn error functions for hard constraints. Our method uses a variant of neural networks we named Interpretable Compositional Networks, allowing us to get interpretable results, unlike regular artificial neural networks. Experiments on 5 different constraints show that our system can learn functions that scale to high dimensions, and can learn fairly good functions over incomplete spaces.
arXiv:2002.09811v4 fatcat:oilv5cgmcrhzfkf4ilu6z4xugq

A 36,000-Year-Old Volcanic Eruption Depicted in the Chauvet-Pont d'Arc Cave (Ardèche, France)?

Sébastien Nomade, Dominique Genty, Romain Sasco, Vincent Scao, Valérie Féruglio, Dominique Baffier, Hervé Guillou, Camille Bourdier, Hélène Valladas, Edouard Reigner, Evelyne Debard, Jean–François Pastre (+2 others)
2016 PLoS ONE  
The chronological succession of the Megaloceros panel superposition described in Féruglio and Baffier [8] is complex. Four phases can be separated (Fig 3C) : 1. First phase of drawings.  ...  Acknowledgments Authors would like to thank Jean-Louis Joron (Laboratoire Pierre Süe, Saclay, France) for sample irradiation using the OSIRIS nuclear reactor of the Commissariat à l'Énergie Atomique et  ...  Baffier). (D) Petroglyphs depicting the Porak volcano eruption and dated from the 5 th millennium BC in the Syunik region of Armenia [3] .  ... 
doi:10.1371/journal.pone.0146621 pmid:26745626 pmcid:PMC4706433 fatcat:yioxroz375d3daqhdxpprvalsm

Hanabi is NP-hard, Even for Cheaters who Look at Their Cards [article]

Jean-Francois Baffier, Man-Kwun Chiu, Yago Diez, Matias Korman, Valia Mitsou, André van Renssen, Marcel Roeloffzen, Yushi Uno
2017 arXiv   pre-print
In this paper we study a cooperative card game called Hanabi from the viewpoint of algorithmic combinatorial game theory. In Hanabi, each card has one among $c$ colors and a number between $1$ and $n$. The aim is to make, for each color, a pile of cards of that color with all increasing numbers from $1$ to $n$. At each time during the game, each player holds $h$ cards in hand. Cards are drawn sequentially from a deck and the players should decide whether to play, discard or store them for
more » ... tore them for future use. One of the features of the game is that the players can see their partners' cards but not their own and information must be shared through hints. We introduce a single-player, perfect-information model and show that the game is intractable even for this simplified version where we forego both the hidden information and the multiplayer aspect of the game, even when the player can only hold two cards in her hand. On the positive side, we show that the decision version of the problem---to decide whether or not numbers from $1$ through $n$ can be played for every color---can be solved in (almost) linear time for some restricted cases.
arXiv:1603.01911v3 fatcat:7cto24av3jh4vfojmewgnui4ii

Hanabi is NP-Complete, Even for Cheaters Who Look at Their Cards

Jean-Francois Baffier, Man-Kwun Chiu, Yago Diez, Matias Korman, Valia Mitsou, André Van Renssen, Marcel Roeloffzen, Yushi Uno, Jean, Francois Baffier, Man-Kwun Chiu, Yago Diez (+5 others)
2016 17 Leibniz International Proceedings in Informatics Schloss Dagstuhl-Leibniz-Zentrum für Informatik   unpublished
This paper studies a cooperative card game called Hanabi from an algorithmic combinatorial game theory viewpoint. The aim of the game is to play cards from 1 to n in increasing order (this has to be done independently in c different colors). Cards are drawn from a deck one by one. Drawn cards are either immediately played, discarded or stored for future use (overall each player can store up to h cards). The main feature of the game is that players know the cards their partners hold (but not
more » ... s hold (but not theirs. This information must be shared through hints). We introduce a simplified mathematical model of a single-player version of the game, and show several complexity results: the game is intractable in a general setting even if we forego with the hidden information aspect of the game. On the positive side, the game can be solved in linear time for some interesting restricted cases (i.e., for small values of h and c). 1 Introduction When studying mathematical puzzles or games, mathematicians and computer scientists are often interested in winning strategies, designing computer programs that play as well (or even better than) humans. The computational complexity field studies the computational
fatcat:6b4nt44rc5dgtl2clopstxjg5a

Jacques Brunet (1942-2017)

Philippe Malaurent, Dominique Baffier
2017 Paleo  
Référence électronique Philippe Malaurent et Dominique Baffier, « Jacques Brunet (1942-2017) », PALEO [En ligne], 28 | 2017, mis en ligne le , consulté le 07 juillet 2020.  ...  AUJOULAT Norbert, ANDRIEUX Claude, MANGIN Alain, CLOTTES Jean, SUMERLY Frédéric, MENU Michel, WALTER Philippe, LORBLANCHET Michel, BRUNET Jacques, VIDAL Pierre, CHEVILLOT Christian, ROUZAUD François  ...  Dominique BAFFIER Sorciers (Angles-sur-l'Anglin, Vienne, France) - International newsletter on Rock art, 18, p. 21-25.  ... 
doi:10.4000/paleo.3065 fatcat:5okpt7pq2zaqromvmndmngpzea

Back to France to Celebrate the Century-Old IUPAC: The 47th IUPAC World Chemistry Congress & 50th General Assembly

Clément Sanchez, Jean-Pierre Vairon
2019 Chemistry International  
Members of the IUPAC2019 organizing team: Stanislas Pommeret, Clémentine Vallet (PCO), Adrian Auger (PCO), Jean-Pierre Vairon, Clément Sanchez, Nicole Moreau, and Nöel Baffier The Year 2019 is a very unique  ...  with a plenary by Sir Cyril Norman Hinshelwood (Nobel Prize in Chemistry, 1956) and an interlude by the Symphonic Orchestra of the Republican Guard, and a reception in the Domaine de Chantilly par François  ... 
doi:10.1515/ci-2019-0201 fatcat:ugwltpav3bgotj37aydebixeia

Affinités picturales, entre expressions symbolistes et recherches identitaires

Christine Peltre
2019 Revue de la BNU  
Baffier pour le Berry, Charles Spindler est l'interprète le plus éloquent et le plus qualifié de la terre d'Alsace » 22 .  ...  Le peintre en son atelier de retour d'Espagne, collection particulière, in Françoise Metz, Stahl, Bernardswiller, ID, 2013, p. 96 4-J-K.  ... 
doi:10.4000/rbnu.2192 fatcat:5744bjtd5bbjpmmmqn3lkpb3ge

Les parois chauffées de la grotte Chauvet-Pont d'Arc (Ardèche, France) : caractérisation et chronologie

Catherine Ferrier, Évelyne Debard, Bertrand Kervazo, Aurélie Brodard, Pierre Guibert, Dominique Baffier, Valérie Feruglio, Bernard Gély, Jean-Michel Geneste, Frédéric Maksud
2014 Paleo  
Maksud, en hommage à François Rouzaud 63 Les parois chauffées de la grotte Chauvet-Pont d'Arc (Ardèche, France) : caractérisation et chronologie Galerie des Mégacéros Salle Hillaire Galerie du  ...  Les griffades et les polis d'ours sont également nombreux (Feruglio et Baffier 2005 ; Philippe et Fosse 2003 ; Fosse et Philippe 2005).  ... 
doi:10.4000/paleo.2730 fatcat:bc2rsllclrf6ne6o4apbs7gfg4

Étude typo-technologique et spatiale de remontages lithiques de Canaule II, site châtelperronien de plein-air en Bergeracois (creysse, Dordogne)

François Bachellerie, Jean-Guillaume Bordes, André Morala, Jacques Pelegrin
2007 Paleo  
Les travaux de François Bachellerie sont financés par une bourse de doctorat pour ingénieur CNRS-Région Aquitaine (BDI).  ...  BAFFIER D. et JULIEN M. 1990 -L'outillage en os des niveaux châtelperroniens d'Arc y -s u r-C u re, in : C.  ... 
doi:10.4000/paleo.782 fatcat:roper4tlazgnlkd2zs4nkt4utq
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