Mascotteis a joint team between INRIA Sophia Antipolis Méditerranée and the laboratory I3S (Informatique Signaux et Systèmes de Sophia Antipolis) which itself belongs to CNRS (Centre National de la Recherche Scientifique) and UNS (University of Nice Sophia Antipolis). Its research fields are Algorithmics, Discrete Mathematics, Combinatorial Optimization and Simulation, with applications to telecommunication networks.

The objectives of the Mascotteproject-team are to design networks and communication algorithms. In order to meet these objectives, the team studies various theoretical tools, such as Discrete Mathematics, Graph Theory, or Algorithmics and develops applied techniques and tools, especially for Combinatorial Optimization and Computer Simulation. In particular Mascotteused in the last year both these theoretical and applied tools for the design of various networks, such as WDM, wireless (radio), satellite, overlay, and peer-to-peer networks. This research has been done within various industrial and international collaborations.

This results also in the production of advanced softwares such as the Mascoptlibrary ( Mascotteoptimization), and ambitious software projects such as the OSA (Open Simulation Architecture) Computer Simulation Architecture.

**Honors:**J-C. Bermond received two prizes: the
prestigious French award (Grand Prix) from the French Academy
of science
*Prix de la Fondation d'entreprise EADS*(informatique) (
http://

**HDR:**Two members of MASCOTTE passed their HDR in March
2010: D. Coudert and S. Pérennes.

Last year Mascotte has strongly increased its international and industrial collaborations with:

**European Collaborations:**A STREP EULER (Experimental
UpdateLess Evolutive Routing), part of FIRE (Future Internet
Research and Experimentation) objective of FP7, started.

**ANR:**A new International ANR with Taiwan GRATEL (Graphs
and Telecomunications) started.

The project develops tools and theory in the following domains: Discrete Mathematics (in particular Graph Theory), Algorithmics, Combinatorial Optimization and Simulation.

Typically, a telecommunication network (or an
interconnection network) is modeled by a graph. A vertex may
represent either a processor or a router or any of the
following: a switch, a radio device, a site or a person. An
edge (or arc) corresponds to a connection between the
elements represented by the vertices (logical or physical
connection). We can associate more information both to the
vertices (for example what kind of switch is used, optical or
not, number of ports, equipment cost) and to the edges
(weights which might correspond to length, cost, bandwidth,
capacity) or colors (modeling either wavelengths or
frequencies or failures) etc. Depending on the application,
various models can be defined and have to be specified. This
modeling part is an important task. To solve the problems, we
manage, when possible, to find polynomial algorithms. For
example, a maximum set of disjoint paths between two given
vertices is by Menger's theorem equal to the minimum
cardinality of a cut. This problem can be solved in
polynomial time using graph theoretic tools or flow theory or
linear programming. On the contrary, determining whether in a
directed graph there exists a pair of disjoint paths, one
from
s_{1}to
t_{1}and the other from
s_{2}to
t_{2}, is an NP-complete problem, and so are all the
problems which aim at minimizing the cost of a network which
can satisfy certain traffic requirements. In addition to
deterministic hypothesis (for example if a connection fails
it is considered as definitely down and not intermittently),
the project started recently to consider probabilistic
ones.

Graph coloring is an example of tool which appears in various contexts: WDM networks where colors represent wavelengths, radio networks where colors represent frequencies, fault tolerance where colors represent shared risk resource groups, and scheduling problems. Another tool concerns the development of new algorithmic aspects like parametrized algorithms.

Theoretical results are described after, with more emphasis on those of Graph Theory (Section ) and Algorithmic Aspects (Section ).

For the last year the main application domain of the project remained Telecommunications. Within this domain, we consider applications that follow the needs and interests of our industrial partners, in particular Orange Labsor Alcatel-Lucent Bell-Labs, but also SMEs' like UbiStorageor 3-Roam.

Mascotteis mainly interested in the design of heterogeneous networks. The project has kept working on the design of backbone networks in particular optical ones (see Section ) but also on wireless access networks (see Section ) and on overlay (Peer to peer) networks (see Section ).

Part of these research is done within the joint laboratory
INRIA-Alcatel-Lucent Bell-Labs, (participation in the ADR
HiMa on autonomous dynamic management of virtual topologies
and within the ANR ECOSCells led by Alcatel-Lucent
Bell-Labs).
Mascottehas also a
contract with Alcatel-Lucent Bell-Labs, on dynamic compact
routing. This collaboration continues through the STREP EULER
which started in October 2010. An emphasis is done on green
networks with low power consumption financed with the ANR
DIMAGREEN. We have also developed two cooperations with SMEs.
The first one is on data storage in peer-to-peer networks
with the SME
UbiStoragewithin
the ANR SPREADS (Safe P2P reliable Architecture for Data
Storage). The second one is on backhaul networks with the SME
3-Roamand AVISTO,
and is funded by the
*région PACA*project RAISOM (Wireless IP Service
Deployment optimization and monitoring) and European fund
FEDER.

More than 11000 lines, developed in Java.

The Dipergrafs project proposes a Java framework for the manipulation of directed hypergraphs. Briefly, a directed hypergraph consists in a set of directed links, each link connecting a set of vertices to another set of vertices. Hypergraphs are used into the fields of network modeling, rational databases, semantic web, expert systems, route planning. In particular, Dipergrafs is designed in order to make it particularly useful in the context of network simulation.

The most important features of Dipergraphs are: it has a vertex-oriented design (in opposite to node-oriented design), that is the graph is seen as a collection of relations between nodes; it imposes no constraint on the type of nodes and vertices (in opposite to frameworks which oblige to follow a certain structure, leading to a lack of flexibility); it provides implementations for common graph operations : navigation (paths, connected components, shortest paths, hop-exploring, etc), graph queries, graph metrics (radius, density, degrees, distance/adjacency/incidence matrices, etc), distributions of vertex metrics; it is mostly usable through a small set of Java classes (in opposite to frameworks whose utilization requires the knowledge of numerous classes); it features graph input/output mechanisms, allowing persistence, serialization, etc; it does not feature any graph rendering tool. Instead bridges to external products dedicated to rendering are provided; it comes with a set of composeable topology generator allowing to quickly instantiate the desired topology.

Dipergrafs is extensively used in the DRMSim project, in which it enables the modeling and simulation of large backbone networks.

Around 30000 lines, developed in Java, collaboration between MASCOTTE and researchers in LaBRI (95 %MASCOTTE).

The expansion of the Internet results in a number of issues: BGP (Border Gateway Protocol) starts to show its limits in terms of the number of routing table entries it can manage. More efficient dynamic routing protocols are thus under investigation. However, because deploying under-development routing protocols on the Internet is not practicable at a large-scale, simulation is an unavoidable step to validate the properties of a newly proposed routing scheme. Unfortunately, the simulation of routing protocols over large networks poses real challenges due to the limited computational capabilities of computers. Existing simulation tools exhibit limitations in terms of the number of nodes they can handle and of the models they propose. This motivated us to conceive and develop DRMSim (Dynamic Routing Model simulator): a network simulator which addresses the specific problem of large-scale simulations of routing models.

DRMSim relies on a discrete-event simulation engine. It proposes a general routing model which accommodates any network configuration. Aside to this, it includes specific models for Generalized Linear Preference (GLP), and K-chordal network topologies, as well as implementations of routing protocols, including the routing protocol proposed in and lightweight versions of BGP (Border Gateway Protocol).

DRMSim is developed in cooperation with LaBRI (Laboratoire Bordelais de Recherche en Informatique, Bordeaux, France).

See also the web page
http://

Developed in Java.

Mascopt
is a Java library distributed
under the terms of the LGPL license which is dedicated to
graph and network processing.
Mascoptincludes a
collection of Java interfaces and classes that implement
fundamental data structures and algorithms. The forthcoming
public distribution of
Mascoptwill appear
under the name of the
openGVEproject,
Mascoptbeing one
implementation of the bridge graph interface [R. Correa,
http://

The main objective of Mascopt( MascotteOptimization) project is to ease software development in the field of network optimization. Examples of problems include routing, grooming, survivability, and virtual network design. Mascopthelps implementing a solution to such problems by providing a data model of the network and the demands, classes to handle data and ready to use implementations of existing algorithms or linear programs (e.g. shortest paths or integral multicommodity flow).

A key feature of Mascoptis to provide a generic linear programming object interface which allows users to program the same way whether the target solver is IBM ILOG CPLEX, GLPK (GNU Linear Programming Kit) or CLP/CBC (accessed through JNI).

Mascopthas intensively been used in the past within Mascotteindustrial cooperation programs for experimentation and validation purposes as for example with Alcatel Space Technologies and Orange Labs. Today, the library is used within the framework of the ANR AGAPE to implement FPT algorithms (work done at LIFO).

See also the web page
http://

Developed in Java ( 80%) and XML, AspectJ, etc. Represent the work of about 7 man/year during the last 5 years.

Component-based modeling has many well-known good properties. One of these properties is the ability to distribute the modeling effort amongst several experts, each having his/her own area of system expertise. Clearly, the less experts have to care about areas of expertise of others, the more efficient they are in modeling sub-systems in their own area. Furthermore, the process of studying complex systems using discrete-event computer simulations involves several areas of non-system expertise, such as discrete-event techniques or experiment planning.

The Open Simulation Architecture (OSA) is designed to enforce a strong separation of the end-user roles and therefore, ensure a successful cooperation of all the experts involved in the process of simulating complex systems.

The OSA architecture is also intended to meet the expectations of a large part of the discrete-event simulation community: it provides an open platform intended to support researchers in a wide range of their simulation activities, and allows the reuse and sharing of system models in the simulation community by means of a flexible and generic component model (Fractal).

Many discrete-event simulators are developed concurrently, but with identical or similar purpose. Another goal of OSA is to favor the reuse and integration of simulation software components and models. To favor reuse, OSA uses a layered approach to combine the modeling, simulation, and related concerns, such as instrumentation or deployment. This ability is demonstrated by the successful integration and reuse of third-party components, such as Scave, the analysis module of Omnet++, or a large number of the James II plugins developed by the University of Rostock. OSA is both a testbed for experimenting new simulation techniques and a tool for real case studies.

OSA is Open Source (LGPL) and is available for download on
the INRIA forge server
http://

See also the web page
http://

Developed in Python and Cython. N. Cohen wrote more than 140 patches and reviewed 75 others.

Sagemath is a free open-source mathematics software aiming at becoming an alternative to Maple and Matlab. Initially created by William Stein (Professor of mathematics at Washington University), Sagemath is currently developed by more than 180 contributors around the world (mostly researchers). It was initially of interest for Mascotte because of its large library in Combinatorics and Graph Theory. This year, impressive improvements have been made to this library. In particular, N. Cohen contributed a lot into the following: 1) implementation of a generic interface between Sage and existing (Mixed Integer) Linear Program solvers, 2) implementation of exact algorithms for common Polynomial/NP-Complete graph problems, often through the use of Linear Programs, and 3) improving Sage's documentation by participating to the writing of a French manual on the use of Sage with 10 other French scientists , .

Sage's Graph and Linear Programing libraries are currently used by Mascotte members to test algorithms or compare their performances, as well as to prove/disprove theoretical conjectures and for teaching purposes in the Master IFI, stream UBINET.

More than 1000 lines, developed in Java.

EPR is a utility software aiming at providing a as-simple-as-possible tool for exporting an Eclipse Java project into a self-contained ZIP file, as well as updating the project website and SVN repository.

See also the web page
http://

More than 3000 lines, developed in Java.

Java4unix proposes a development framework which simplifies the use of Java for UNIX software programming/distribution. Until now, Java could hardly be used for the development UNIX applications because invoking Java applications from the UNIX shell must be done through an explicit call to the Java virtual machine and writing simple things in Java often requires long coding. Java4unix aims at filling those two gaps by providing a UNIX installer for java applications, turning them to standard UNIX application and a framework that UNIX programmers may use to manipulate files/text, etc.

The following applications/projects already make use of java4unix: java4unix itself, drmsim, dipergrafs, lmu, epr, mascsim, fff, etc.

See also the web page
http://

Around 10000 lines, developed in Java.

Mascsim is a distributed discrete event simulator whose main target is to be easy to use.

Unlike most discrete-event simulators, the researcher who is using Mascsim is required to provide only the bare minimum material needed for the simulation: a model for the system, a set of events describing what is going on in the system, as well as a set of metrics of interest.

The simulation process is then entirely automatized, as concerns the distribution of the simulation campaign on the grid, the plot of result graphs or whatever other daunting task.

See also the web page
http://

Around 3000 lines, developed in Python.

P2PVSim is a simple discrete-event simulator created for analyzing theoretical properties of peer-to-peer live video streaming algorithms. Implemented in Python it was designed with clarity and extensibility in mind from the beginning. At the same time, a lot of work was put into the performance and scalability aspects of the software. Currently it is meant for simulating overlays of a few thousand peers running simple control protocols.

Network design is a very wide subject that concerns all
kinds of networks. For telecommunications networks it can be
either physical networks (backbone, access, wireless, ...) or
virtual (logical) ones. The objective is to design a network
able to route a (given, estimated, dynamic, ...) traffic
under some constraints (e.g. capacity) and with some quality
of service (QoS) requirements. Usually the traffic is
expressed as a family of requests with parameters attached to
them. In order to satisfy these requests, we need to find one
(or many) path(s) between their end nodes. The set of paths
is chosen according to the technology, the protocol or the
QoS constraints. For instance, optical backbones use the WDM
technology to take better advantage of the capacity of the
optical fibers often already installed. This is achieved
through the multiplexing of several wavelength channels onto
the same fiber. In that case a resource allocation is an
optical channel, which consists of a path and a wavelength
assigned on each link along the path, and is called a
*lightpath*. If wavelength translation is performed in
optical switching, then to each channel may be assigned
different wavelengths on each link along the path; otherwise
the wavelength continuity constraint must be satisfied on all
links along the path. Of course, two lightpaths sharing a
link must use different wavelengths on that link. The design
can be done at the conception of the network (i.e. when
conceiving a virtual network in
MPLSwhere we have
to establish virtual paths) or to adapt the network to
changes (failures, new link, updates of routers, variation of
traffic, ...). Finally there are various optimization
criteria which differ according to the point of view: for a
network user they are related to his/her satisfaction
(minimizing delays, increasing available bandwidth, ...),
while for a network operator, economics criteria like
minimizing deployment and operating costs are more
important.

This very wide topic is considered by a lot of academic and industrial teams in the world. Our approach is to attack these problems with tools from Discrete Mathematics and to consider mainly telecommunications networks.

In a WDM network, routing a connection request consists
in assigning a route in the physical network and a
wavelength to this connection request. When each request
uses at most
1/
Cof the bandwidth of the
wavelength, we say that the grooming factor is
C. That means that on a given edge of the network we
can groom at most
Crequests on the same wavelength. With this
constraint the objective can be either to minimize the
number of wavelengths (related to the transmission cost) or
minimize the number of Add/Drop Multiplexers (ADM) used in
the network (related to the cost of the nodes). We
addressed this problem in various
WDMnetwork
topologies with the goal of minimizing the total number of
ADMs required.

This year, we have provided optimal constructions in
bidirectional WDM rings with All-to-All uniform unitary
traffic when
C= 1, 2, 3and
k(
k+ 1)/2(
k1) for infinite congruence classes,
and have proposed an approximate construction for
C= 2, 3
. We have also studied the
all-to-all traffic grooming on unidirectional rings with
grooming factor
Cand with the extra constraints that the traffic
between a subset of vertices must be served with grooming
factor
C^{'}. We provided optimal constructions for
C= 4and
C^{'}= 1, 2, 3
. Finally, in
, we have surveyed the main
results obtained on traffic grooming, including complexity
and hardness results, optimal constructions, approximation
algorithms, ILP formulations and heuristic algorithms.

We have proposed a new framework, based on linear programming with column generation, for shared segment protection in WDMwith grooming capability , . The objective is to determine for every working path a set of protection segments(sub-paths) that are used to recover any node or link failure. The resources devoted to protection are shared among node and link disjoint working paths.

In production networks, traffic evolution, failures and
maintenance operations force to adapt regularly the current
configuration of the network (virtual topology, routing of
connections). The routing reconfiguration problem in
WDMnetworks is
thus to schedule the
*migration*of established lightpaths from current
routing to a new pre-computed one while minimizing service
disruptions. We have shown in the past the relations
between this problem and the
*graph searching problem*(see also Section
).

This year, we have focussed on the tradeoffs between the total number and the number of simultaneous interruptions that occur during the reconfiguration process, proving in particular that the knowledge of one parameter does not help to optimize the other , .

The minimization of ICT energy consumption has become a priority with the recent increase of energy cost and the new sensibility of public, governments and corporations towards energy consumption. ICT alone is responsible of 2% to 10% (depending on the estimations) of the world power consumption. For example, it is estimated that switches, hubs, routers account for 6 TWh per year in the US.

Several studies exhibit that the traffic load of the routers only has a small influence on their energy consumption. Hence, the power consumption in networks is strongly related to the number of active network elements, such as interfaces, line cards, base chassis,... In , , , we define and model formally the problem of finding a routing with the goal of minimizing the (weighted) number of active network elements. Then, we prove that this problem is not in APX, that is there is no polynomial-time constant-factor approximation algorithm. Thus, we propose a heuristic algorithm for this problem and we present a study on specific topologies, such as trees and complete graphs, that provide bounds and results useful for real topologies. Finally, we discuss the impact of energy efficient routing on the stretch factor and on fault tolerance.

The transmission of an optical signal in a fiber causes small phase shifting and power loss forcing to regenerate the signal after a certain distance (e.g. 1000km). We have investigated the problem of minimizing the total number of locations to place the regenerators in a WDM network . We established the complexity and in-approximability of the problem, and provided approximation algorithms and exact polynomial time algorithms whenever possible.

Motivated by the minimization of the number of wavelengths needed to route a set of requests in a WDMnetwork, we studied the natural linear programming relaxation of the path coloring problem . We prove constructively that finding an optimal fractional path coloring is Fixed Parameter Tractable (FPT), with the degree of the tree as parameter. We also show a approximation algorithm for the path coloring problem in bounded degree trees, improving on existing results.

We have also investigated the impact of topological properties, and in particular complex networks properties, on the routing in backbone networks . We focussed in particular on the overall number of ports used in router nodes.

.

Mascottehas
conducted an intense research effort on wireless access
networks. From the technological and architectural point of
view, the field is broad, from mesh (or multi-hop cellular)
networks to
*ad-hoc*and sensor networks. Nevertheless, many
questions and approaches are generic from an algorithmic and
structural viewpoint.

In particular, we have studied three of the most prominent performance metrics for radio networks. Using combinatorial optimization and centralized algorithmic with a network design flavor, transport capacity and energy consumption of the networks have been studied. Using distributed algorithmic with a protocol flavor, fast data gathering and call scheduling are investigated. Our approach is complementary with those developed in other INRIA project-teams such as Planete, Maestro, Swing(ex Ares) or Pops. The complementarity has been exploited through a joint Ph.D. between Maestroand Mascotteand, recently, through an ANR VERSO project in which Maestro, Mascotteand Swingare involved.

At the international level, our researches cooperate with some groups in renowned research centers such as CTI of Patras in Greece, Universities of Roma or Salerno in Italy, the Technion Institute in Israël, SFU in Vancouver, Canada, UFC, Universidade Federal do Ceará, Fortaleza, Brazil, or the University of Sao Paulo in Brazil.

We studied a wide range of issues of wireless networks, from the design of efficient cross-layer medium access, call scheduling and routing techniques to energy efficient optimization. We developed theoretical tools for analyzing and evaluating dynamic networks. Some graph coloring problems motivated by channel assignment in wireless networks are detailed in Section and the optimization techniques and wireless simulation tools that we have developed are also cited in Section .

We investigated network optimization problems related to the design and configuration of wireless microwave backhaul. We have proposed a chance-constrained programming approach to determine the optimal bandwidth assignment for the links of a microwave backhaul network under outage probability constraints . Moreover, we have presented mathematical models to generate power-efficient radio configurations as a function of the network traffic , . In addition, in collaboration with the SME 3Roam (see Section ), we have developed an optimization tool, 3Link, for helping the design of microwave links .

Several works of Mascottehave dealt with gathering (data collection) in wireless multi hop networks when interferences constraints are present.

In particular we consider interference constraint
modeled by a fixed integer
d1, which implies that nodes within distance
din the graph from one sender cannot receive messages
from another node. We give optimal protocols for
d= 1when the network is a tree
and the destination node is the root of the tree. In
, we consider the case where
buffering is allowed in intermediate nodes and in
, the case where no buffering
is allowed.

Distributed call scheduling in wireless networks is a challenging problem to tackle. Indeed, even when interferences are not considered, computing an optimal call scheduling with local information is still an open question. Due to interference constraints, incident links cannot be simultaneously activated, otherwise transmissions will fail. In , we design the first fully distributed local algorithm with the following properties: it works for any arbitrary binary interference model; it has a constant number of mini-slots of control (independent of the size of the network and the values of the queues); and it needs no knowledge. We also give sufficient conditions for stability under Markovian assumptions.

Another way to deal with the distributed call scheduling problem is in terms of Round Weighting Problem (RWP). In , we develop the Cut Covering Problem (CCP) and prove that it is equivalent to RWP. We develop a primal/dual algorithm combining line and column generation to deal with the exponential number of variables and constraints of CCP.

.

Traditional means to store data are dedicated servers or magnetic tapes. These solutions are reliable but expensive. Recently, hard disks and bandwidth have become cheaper and widely available, allowing new forms of data storage on distributed, peer-to-peer (P2P) architectures. To achieve high durability, such P2P systems encode the user data in a set of redundant fragments and distribute them among the peers. These systems are cheap to operate, but their highly distributed nature raises questions about reliability, durability, availability, confidentiality, and routing of the data. An abundant literature exists on the topic of P2P storage systems. Several large-scale self-managing distributed systems have been proposed, including Intermemory, Ocean Store, Freenet, PASTRY, CFS, Total Recall. However, few analytical models have been proposed to estimate the behavior of the system (the data durability, resource usage) and understand the trade-offs between the system parameters.

We model a general storage system by using a Markov chain model in , . This model allows us to take into account the effects of disk failures along with the time consumed by the self-repairing process. We confirm that a lazy repair strategy can be employed to amortize the repairing cost, mainly bandwidth. We then derive closed-form mathematical expressions that estimate the system average behavior. These formulas give a good intuition of the system dynamics. Our contribution is a guideline to system designers and administrators to choose the best set of parameters.

We study in , , the impact of different data placement strategies on the system performance. This study is motivated by practical peer-to-peer storage systems that store data in logical neighbors. We use simulations and combinatorial models to show that, without resource constraints, the average system behaviour is the same no matter which placement policy is used. However, the variations in the use of bandwidth are much burstier under the local policies (in which the data are stored in logical neighbors). When the bandwidth is limited, these bursty variations induce longer maintenance time and henceforth a higher risk of data loss.

A good overview of the general approaches used for all these studies can be found in the Ph.D. thesis of J. Monteiro . This thesis aims at providing tools to analyze and predict the performance of large scale data storage systems. Thus, different techniques are studied and applied. They range from formal analysis (using Markov chains and fluid models) to simulations and experimentation (using Grid5000 platform).

.

The works related to simulation and optimization tools address two kinds of issues: issues related to the development of the tools and their associated methodology, and issues related to the use of these tools in order to investigate a particular problem or assess the performances or properties of a particular system.

Since 2005, Mascotteis developing a discrete event simulation architecture, named OSA, whose aim is to investigate how new software engineering techniques, such as component-based frameworks or Aspect Oriented Programming can help improving the simulation methodology , especially in terms of software reuse. However, an important issue to solve when considering the reuse problem, is that of standardization, hence our significant involvement in the current standardization efforts led around the DEVS formalism , . Indeed, rigorous formalisms, such as the Discrete Event Systems Specification (DEVS) are necessary to express the behavior of the model to be simulated in a non-ambiguous and reusable way. In , we provide a comprehensive survey of various usages for the particular Cell-DEVS formalism. In a more general way, we also put efforts in federating the scientific community on such simulation issues, by organizing conferences and editing journals special issues, such as .

Our efforts on simulation development also apply to more specific, application oriented works, such a in , in which we extend the Omnet++ network modeling Framework (INET) to support directional and asymmetrical wireless communications or in , in which we address the challenge of simulating routing schemes in very large scale network topologies. In addition, in , we evaluate the performance of routing protocols in MANETs, in which the connectivity patterns are expressed using the concept of evolving graphs.

.

Mascotteprincipally investigates applications in telecommunications via Graph Theory (see other objectives). However it also studies a number of theoretical problems of general interest. Our research mainly focused on graph coloring and some other problems arising from networks'problems.

Coloring and edge-coloring are two central concepts in Graph Theory. There are many important and long-standing conjectures in these areas. We are trying to make advances towards such conjectures, in particular Hadwiger's conjecture, the List coloring Conjecture and the Acyclic Edge-coloring Conjecture.

We are also interested in coloring problems arising from
some practical problems: improper coloring,
L(
p,
q)-labeling and directed star
arboricity. The first two are both motivated by channel
assignment and the last one by problems arising in WDM
networks. For many practical problems are posed in a
dynamic setting, we study on-line coloring.

We also study some other variants of coloring like non-repetitive coloring or frugal coloring.

*Edge-coloring*: The most
celebrated conjecture on edge-coloring is the List coloring
Conjecture asserting that the chromatic index (minimum
number of colors used in a proper coloring of the edges) is
always equal to the list chromatic index. In list-coloring,
each edge is assigned a list of colors. The list chromatic
index is the smallest size of the tables, such that, for
any assignment of colors in any table, each edge may choose
a color in its own table to obtain a proper coloring of the
graph (no two incident edges have the same color). Together
with Vizing's Theorem it implies the following conjecture :
For any graph
Gwith maximum degree
, the list chromatic index is at most
+ 1. In
, we give a short proof of a
result of Borodin showing that this later conjecture holds
for planar graphs of maximum degree at least 9.

*Improper coloring*: We studied a
weighted improper coloring problem motivated by a frequency
allocation problem. It consists of associating to each
vertex a set of
p(
v)(weight) distinct colors
(frequencies), such that the set of vertices having a given
color induces a graph of degree at most
k(the case
k= 0corresponds to proper
coloring). The objective is to minimize the number of
colors. In
,
, we propose approximation
algorithms to compute such a coloring for general graphs,
and specific better approximation algorithms for grid and
hexagonal graphs.

* L(
p,
q)-labeling*: An

In addition,
L(1, 1)-labeling of planar graphs
is closely related to the notion of facial coloring which
we study in
.

*Directed star arboricity*: A
*galaxy*is a vertex-disjoint union of stars. In
, we show that the minimum
number of galaxies needed to cover the arc-set of any
digraph
Dwith maximum degree
(
D)is upper bounded by
2
^{-}(
D) + 1and is at most 3 in
subcubic digraphs. We study the relationship of this
problem with a more general problem modeling multicast in
WDM networks.

*On-line coloring*: Several
on-line algorithms producing colorings have been designed.
The most basic and most widespread one is the greedy
algorithm. The
*Grundy number*of a graph
G, denoted by
(
G), is the largest number of
colors provided by the greedy algorithm according to some
ordering of the vertices of
G. It is easy to see that
(
G)
(
G)
(
G) + 1, where
(
G)is the chromatic number of
Gand
(
G)its maximum degree. We prove
that these to upper bounds are algorithmically useless: in
, we show that for every fixed
c1it is CoNP-Complete to decide if
(
G)
c×
(
G)while in
, we prove that for any
positive integer
k, it is NP-complete to decide if
(
G)
(
G) + 1-
k. On the other hand, we prove
that it is FPT to decide if a graph on
nvertices has a greedy coloring with at most
n-
kcolors. The first
NP-completeness was obtained by considering the Grundy
number of graph products, which we studied further in
. We also gave some complexity
results on
b-colorings, which is a manner of improving colorings
on-line
.

In the
*Weighted Coloring Problem*(WCP), the weight of a
proper coloring is the sum of the weights of its color
classes, where the weight of a color class is the weight of
a heaviest vertex belonging to it. Minimizing this weight
is NP-hard in general. In
, we study the WCP on P4-sparse
graphs.

Motivated by their importance when dealing with problems of network design, the team has been interested in the study of several graph metrics related to distances in graphs.

*Wiener index*: The Wiener index
W(
G)of a graph
Gbeing defined as the sum of the distance between all
pairs of vertices, it also represents the mean distance
between vertices in the graph. It has also been used in
chemistry whereit represents properties of molecules. In
, we consider the relation
between the Wiener index of a graph
Gand its line graph
L(
G). We show that if
Gis of minimum degree at least two, then
W(
G)
W(
L(
G))and that equality may be
achieved whatever be the girth of
G.

*Wiener index of specific recursive
graphs*: In
,
, we are here considering a
very specific network on which we are able to give a closed
formula for the Wiener Index. The proof is of particular
interests for other network models relying on similar
recursive structures, as found in fractal models. In
, we extend our approach to a
stochastic version of ZRG in which layers of triangles are
added with probability p.

*Steiner tree*: Given a graph with
costs on edges, prizes at vertices and a target set, the
Prize Collecting Steiner Tree (PCST) problem is to find a
tree interconnecting vertices in the target set that has
minimum total cost on edges and maximum total prize at
vertices. In
, we establish two risk models
for the PCST problem with uncertain costs and prizes and
propose polynomial-time algorithms for these problems on
2-trees, respectively. Our study shows that the risk models
have advantages over the traditional robust optimization
model.

.

Mascotteis also interested in the algorithmic aspects of Graph Theory. In general we try to find the most efficient algorithms to solve various problems of Graph Theory and telecommunication networks.

This year we mainly investigated algorithmic problems arising in complex networks like the Internet or social networks. In this kind of networks, problems are becoming harder or impracticable because of the size and the dynamicity of these networks.

One way to handle the dynamicity is to provide (distributed) fault tolerant algorithms. We considered self-stabilizing algoritms for the gathering problem, randomized algorithms for the routing (tolarating some fault in routing tables for the routing problems). Besides, the more an algorithm uses local information, the easier it is to update/correct the behaviour of the algorithm. In this direction, we investigated communication problems through game theory. We also studied the power of a communication model using only localized information, i.e., we study what can be computed using this communication model.

Finally, large scale networks have some specific structural properties that may be usefully taken into account in the design of algorithms. We used graph theory to model the complex interactions between individuals in the spread of a disease. More generally, we study structural properties of networks through graph searching games.

Several of the works below take place in the project DCR (see Section ) and the STREP EULER (see Section ).

We address dynamic large scale emerging networks, e.g., mobile sensor networks and we propose to extend the Population Protocols communication model suited for such networks with the notion of Cover Times . Cover Times abstract the interaction characteristics of mobile agents and allow the design of fast converging protocols and the evaluation of their convergence time (this is impossible in the original model). In the new model we study a basic problem in sensor networks - the problem of information gathering. We show a lower bound for any protocol to solve this problem and we propose an optimal solution. To achieve fault-tolerance in the protocols designed in the new model, a generic self-stabilizing transformer is developed . This is an automatic technique to convert a protocol to its self-stabilizing version. As a further extension and as another basic tool, a self-stabilizing phase-clock algorithm is developed . This is a synchronization tool that simulates logical time in an asynchronous system. It enables a protocol designer to organize a protocol execution into phases and thus, simplifies his task.

Due to the dynamicity of large scale networks like the Internet, routing tables are not resilient and it is important for the QoS to design fault tolerant routing algorithms. We designed efficient routing probabilistic algorithms supporting a bounded number of faults in some particular topologies , .

In highly distributed systems, it might be often unrealistic to assume that the resources of the system are directly accessible and controllable by a centralized authority. Therefore, we consider communication problems arising in networks with autonomous or non-cooperative users. In such a scenario, users pursue their own selfish strategies and the system evolves as a consequence of the interactions among them. The scenario is thus characterized by the conflicting needs of the users aiming to maximize their personal profit and of the system wishing to compute a socially efficient solution , . In particular, we study the performances of Nash equilibria in isolation games .

We have also used graph theory to model the complex interactions between individuals in the spread of a disease. While our focus was on infectious diseases such as HIV , it was recently suggested that chronic diseases may also have a spreading component through the adoption of behavioral norms. This was shown with a new model of obesity , in which individuals exchange food and physical activity behaviours in a network, which results in weight changes.

Pursuit-evasion encompasses a wide variety of combinatorial problems related to the capture of a fugitive residing in a network by a team of searchers. The goal consists in minimizing the number of searchers required to capture the fugitive in a network and in computing the corresponding capture strategy. We investigated the two main variants of these games.

Graph searching, where the fuggitive is arbitrary fast and moves simultaneously to the searchers, has been widely studied for its close relationship with graph decompositions .

The "Cops and Robber Games" are turn-by-turn games. We investigated two generalizations of the game introduced by Quilliot, Nowakoski and Winkler in 1983. We proved complexity results, we gave algorithmic lower bounds on the number of cops needed when the robber is fast and we provided structural characterization of graphs where one cop is sufficient to capture a fast fugitive able to hide , .

We continue our study of Fixed Parameter Tractable
algorithms. An out-tree
Tis an oriented tree with exactly one vertex of
in-degree zero and a vertex
xof
Tis called internal if its out-degree is positive.
In
, we design randomized and
deterministic algorithms for deciding whether an input
digraph contains a subgraph isomorphic to a given out-tree
with
kvertices.

A
(
p,
,
k)-network is valid if for any
choice of
inputs and
koutputs, there exist
pedge-disjoint paths from the inputs to the outputs.
In
, we wish to determine
N(
p,
,
k), the minimum number of nodes
in a valid
(
p,
,
k)-network. In many cases, we
provide asymptotically tight bounds for
N(
p,
,
k).

Contract between Alcatel-Lucent Bel-Labs, INRIA and LaBRI (Bordeaux) on Dynamic Compact Routing Schemes.

Mascotteis part of the join laboratory INRIA / Alcatel-Lucent Bell-labs France within the ADR HiMa (research action on High Manageability) and works on autonomous dynamic management of virtual topologies (the ADR finances a Ph.D. student).

(
http://

On Wireless IP Service Deployment optimization and monitoring.

"Convention de recherche encadrant une bourse CIFRE" on
the topic
*Outils algorithmiques pour la détection des
communautés*.

Grant for a Ph.D. student (N. Vieira Nepomuceno)
cofinanced by the SME 3-Roam and the
*région PACA*on optimization and dynamic routing in
wireless backhaul networks.

The objectives of the project DIMAGREEN (DesIgn and MAnagement of GREEN networks with low power consumption) are to introduce and analyze energy-aware network designs and managements in order to increase the life-span of telecommunication hardware and to reduce the energy consumption together with the electricity bill.

(
http://

The project AGAPE (Parametrized and exact graph algorithms) is led by Mascotteand implies also LIRMM (Montpellier) and LIFO (Orléans). The aim of AGAPE is to develop new techniques to solve exactly NP- hard problems on graphs. To do so, we envisage two approaches which are closely related ways to reduce the combinatorial explosion of NP-hard problems through exponential exact algorithms and fixed-parameter tractability.

(
http://

The project SPREADS (Safe P2p-based REliable Architecture for Data Storage) is led by the SME UbiStorage; other partners are the INRIA teams Mascotteand REGAL in Rocquencourt and Eurecom and LACL Paris XII. It concerns the evaluation and optimization of a peer-to-peer based reliable storage system for which simulations of very large peer-to-peer systems will be done using OSA. It has got the approbation and label of the “pôle de compétitivité” SCS.

The ECOSCells (Efficient Cooperating Small Cells) project aims at developing the algorithms and solutions required to allow Small Cells Network (SCN) deployment. The consortium gathers industrial groups, together with 3 SMEs and 6 research institutes: Alcatel-Lucent Bell Labs (leader), Orange Labs, 3ROAM, Sequans, Siradel, INRIA teams Maestro, Mascotteand Swing, Université d'Avignon et des Pays de Vaucluse, Laboratoire des Signaux et Systèmes / Supelec, LAAS and Eurecom.

(
http://

The USS-SimGrid project aims at Ultra Scalable Simulations with SimGrid. This tool is leader in the simulation of HPC settings, and the main goal of this project is to allow its use in the simulation of desktop grids and peer-to-peer settings.

*Réseaux de communications*, working group of GDR ASR,
CNRS. (
http://

*Action Graphes*, working group of GDR IM, CNRS. (
http://

On Algorithmic Principles for Building Efficient Overlay Computers (AEOLUS), in collaboration with 21 European universities and coordinated by University of Patras, Greece.

The goal of AEOLUS is to investigate the principles of and develop algorithmic methods for building an overlay computer that enables efficient and transparent access to the resources of an Internet-based global computer.

Mascotteis the leader of Sub-Project 2 on resource management.

The work within this subproject focuses on the study of fundamental issues for accessing and managing communication resources in an overlay computer. Our research addresses novel and challenging algorithmic issues for efficient resource discovery and querying like construction of overlay networks, query routing and execution, and for sharing critical resources like bandwidth.

On Graph coloring: theoretical and algorithmic aspects.

On Graph coloring: theoretical and algorithmic aspects.

STREP EULER (Experimental UpdateLess Evolutive Routing) is part of FIRE (Future Internet Research and Experimentation) objective of FP7. It aims at finding new paradigms to design, develop, and validate experimentally a distributed and dynamic routing scheme suitable for the future Internet and its evolution. The STREP EULER gathers 7 partners: Alcatel-Lucent Bell (leader) (Antwerp, Belgique), IBBT (Ghent, Belgium), UCL (Louvain, Belgium), RACTI (Patras, Grece), UPC (Barcelona, Spain), UPMC (ComplexNetworks, Paris 6), INRIA (MASCOTTE, GANG, CEPAGE). MASCOTTE is the leader of WP3 on Topology Modelling and Routing scheme experimental analysis.

Joint team EWIN (Efficient algorithms in WIreless Networks) with the Departamento de Computação of Universidade Federal do Ceará of Fortaleza (Brazil).

(
http://

GRATEL (Graphs and Telecomunications) has been started in collaboration with LABRI Bordeaux, UJF Grenoble and three partners in Taiwan: Sun Yat-sen University, the National Taiwan University and Academia Sinica.

University of Southern Denmark, Odensee, Denmark, February 23-June 18, 2010 (4 months);

Universidade Federal do Ceara, Fortaleza, Brazil, December 11-18, 2010 ( 1 week);

Universidade Federal do Ceara, Fortaleza, Brazil, December 2-19, 2010 (2 weeks);

Lehrstuhl II fur Mathematik, RWTH Aachen - Aachen, Germany, December 13-17, 2010 (1 week);

Universidade Federal do Ceara, Fortaleza, Brazil, December 10-January 4, 2010 (3 weeks);

Dipartimento di Informatica ed Applicazioni “Renato M. Capocelli” of the Università di Salerno, Salerno, Italy, July 15-August 31, 2010 (1 month 1/2);

Lehrstuhl II fur Mathematik, RWTH Aachen - Aachen, Germany, February 12- March 15 2010 and December 13-17, 2010 (1 month 1/2);

LIFO, Université d'Orléans, Orléans, France, July 26-30, 2010 (1 week);

Universidade Federal do Ceara, Fortaleza, Brazil, December 03-12, 2010 (1 week);

Universidad Adolfo Ibañez, Santiago, Chile, February 1-7 and July 26-August 6, 2010 (3 weeks);

Dipartimento di Informatica ed Applicazioni “Renato M. Capocelli” of the Università di Salerno, Salerno, Italy, July 15-August 31, 2010 (1 month 1/2);

S.F.U. Vancouver, Canada, january 26- April 16, 2010 (3 months).

Visit to Universidade Federal do Ceará, Fortaleza, Brazil, (from July 23 to August 24, 2010 and from December 22, 2010 to January 15, 2011);

Visit to McGill University, Montreal, Canada (May 1-31, 2010); Visit to National Sun Yat-sen University, Kaohsiung, Taiwan (July 11-31, 2010); Visit to National Taiwan University, Taipei, Taiwan (August 1-15, 2010);

Visit to Alcatel-Lucent Bell labs, Antwerpeen, Belgium, (March 11, 2010); Visit to CITI laboratory, Lyon, France (May 27-28, 2010); Visit to LIRMM, Montpellier, France (November 4-5, 2010);

Visit to Carleton University, Ottawa, Canada (July 16-August 20, 2010);

Visit to Shenzhen Institute of Applied Technology, Shenzhen, China (May 2010); Tencent Inc., Shenzhen, China (May 2010); LIAMA, Beijing, China (May 2010); Ministry of Education, Beijing, China (May 2010); Chinese Academy of Sciences, Beijing, China (May 2010); CreateNet, Trento, Italy (June 2010); University of Buenos Aires, Buenos Aires, Argentina (November 2010); University of Sao Paulo, Sao Paulo, Brazil (November 2010); Ministry of Culture, Brasilia, Brazil (November 2010); Ministry of Science and Technology, Brasilia, Brazil (November 2010); CNPq, Brasilia, Brazil ( November 2010); PUC Rio, Rio de Janeiro, Brazil (November 2010); Federal University of Rio de Janeiro (UFRJ), Rio de Janeiro, Brazil (November 2010); State Secretary for Science and Technology, Rio de Janeiro, Brazil (November 2010);

Visit to Zheijang Normal University, Jinhua, China, (October 28-November 6, 2010); Visit to LIAFA, University Paris 7, (January 20-22, March 08-11, 2010); Visit to LIRMM, University Montpellier 2, (May 17-20, 2010) Visit to LABRI, University of Bordeaux 1, (June 21-24 2010); Visit to G-SCOP, University Joseph Fourier, Grenoble (November 24-26, 2010);

Visit to Univ. Catholique de Louvain, Louvain-La-Neuve (December, 7-10, 2010);

Visit to the Communication Networks Institute, Dortmund University of Technology, (September 29, 2010);

Visit to RWTH Aachen University, Aachen, Germany (May 16-29, 2010); Visit to Universidade Federal do Ceará, Fortaleza, Brazil, (September 25 - October 5, 2010);

Visit to Universidade Federal do Ceará, Fortaleza, Brazil, (April 1-10, 2010); Visit to McGill University, Montreal, Canada (May 1-31, 2010);

Visit to University of Rostock, Rostock, Germany (May 25 - June 25, 2010);

Visit to Universidade Federal do Ceará, Fortaleza, Brazil, (April 1-30 2010); Visit to National Sun Yat-sen University, Kaohsiung, Taiwan (July 11-31, 2010); Visit to National Taiwan University, Taipei, Taiwan (August 1-15, 2010); Visit to LIRMM, Montpellier, France (October 25-November 5, 2010).

expert for DRTT, and various
projects outside France (Canada,Qatar, ...); member of
the comité de sélection of
*61me section of UNS*; responsible of the
*Pôle ComRed*of I3S; member of the Ph.D. committee
of the University of Marseille, member of the
*comité de sélection des ATER*;

expert for the National Sciences and
Engineering Research Council of Canada (NSERC) and the
ANR (ARPEGE, JC-JC, SIMI); Member of the
*comité du suivi doctoral*of INRIA Sophia
Antipolis (since January 2009); Member of
*comité de sélection*27e section for UCBL, Lyon,
2010;

member of the
*comité de sélection Maitre de Conférences*,
University of Marseille 1, Marseille, May 2010;

expert with the European Commission; expert for the distribution of European Structural Funds with the Czech Ministry of Research and decision panel member; member of expert panel of EC PARADISO project; member of scientific committee of the STIC AmSud programme; member of the selection committee of several CNRS programmes (eg PICS, conventions, LIAs, GDRIs...); member of Working Group for the preparation of FP 8, Ministry of Research, France; member of the National Working Group for the monitoring of FP7, Ministry of Research, France;

member of I3S laboratory committee;

member of the
*comité de sélection Maitre de Conférences*,
University of Nice Sophia-Antipolis, April-May 2010;
member of the I3S laboratory committee; member of the
*conseil de l'ecole doctorale I2S*,
Montpellier;

responsible of a new international
master of science at University of Nice Sophia
Antipolis, stream UBINET of the master IFI (
http://
*Conseil de Département*(Department Committee) of
IUT Nice since 2007.

member of the
*comité de sélection des ATER*and of the
*comité de sélection du poste MCF27*IUT.

Combinatorics Probability and Computing, Computer Science Reviews, Discrete Mathematics, Discrete Applied Mathematics, Journal of Graph Theory, Journal Of Interconnection Networks (Advisory Board), Mathématiques et Sciences Humaines, Networks, Parallel Processing Letters the SIAM book series on Discrete Mathematics, Transactions on Network Optimization and Control , Discrete Mathematics, Algorithms and Applications;

Discrete Applied Mathematics (since September 2010);

Journal of Parallel and Distributed Computing (Academic Press), Parallel Processing Letters (World Scientific), Journal of Interconnection Networks (World Scientific), Wireless Networks (Springer).

Pôle ResCom du GDR ASR du CNRS
(since 2005);
*Rencontres francophones sur les aspects
algorithmiques des télécommunications*(AlgoTel);

*ICST Intl. Conf. on Simualtion Tools and
Techniques*(SIMUTools);

Chair of the
*Strategic Forum of the European Alliance for
Innovation*;

*Journées Combinatoire et Algorithmes du Littoral
Méditerranéen*(JCALM);
*Journées Graphes et Algorithmes*(JGA).

*11es Journées Doctorales en Informatique et
Réseaux*, Sophia Antipolis, France, March 24-26,
2010; Chairs: F. Giroire and D. Mazauric.

*3rd Czech-Sloveno-French Workshop on Graph
coloring*, Puyloubier, France, August 30-September
3, 2010; Organizer: F. Havet;

*4th International Workshop on OMNeT++*.
Co-located with Simutools 2011. Barcelona. Spain.
March, 21, 2011. Organizer: J-C. Maureira;

*1st edition of the International workshop "Toward
Evolutive Routing Algorithms for
scale-free/internet-like NETworks "*(TERA-NET 2010)
that was held in conjonction with ICALP 2010 -
Bordeaux, France - July 5th, 2010; Organizer: N.
Nisse.

*5th International Conference on FUN with
Algorithms*(FUN'10), Ischia Island, Italy (June 2-4,
2010),
*8th French Combinatorial Conference*(8FCC),
Orsay, France (June 28th - July 2nd, 2010);

*9th International Symposium on Experimental
Algorithms*(SEA'10), Ischia Island (Napoli), Italy
(May 20-22, 2010);

*1st IEEE International Workshop on Collaborative
Modeling
&Simulation*(CoMetS?10), TEI of Larissa,
Greece (June 28- 30, 2010);
*International Conference on High Performance
Computing
&Simulation*(HPCS'10),
Caen, France (June 28 - July 2, 2010);
*Symposium On Theory of Modeling and Simulation DEVS
Integrative M
&S
Symposium*(DEVS'10), Orlando, FL, USA (April 11-15,
2010);

*11es Journées Doctorales en Informatique et
Réseaux*(JDIR'10), Sophia Antipolis, France (March
24-26, 2010). (co-chair);

*36th International Workshop on Graph Theoretic
Concepts in Computer Science*(WG'10), Zarós, Crete,
Greece (June 28 - 30, 2010),
*12th Journées Graphes et Algorithmes*(JGA'10),
Marseille, France (November 8-10, 2010);

*3rd international workshop on OMNeT++*, Malaga,
Spain (March, 15-19, 2010) (co-chair);

JDIR'10 (co-chair),
*MAnifestation des JEunes Chercheurs en Sciences et
Technologies de l'Information et de la
Communication*(MajecSTIC'10), Bordeaux, France
(October 13-15, 2010);

*12th rencontres francophones sur les aspects
algorithmiques des télécommunications*(AlgoTel'10),
Belle Dune, France (June 16-19, 2010), JDIR'10;

JDIR'10, MajecSTIC'10.

Bordeaux graph Workshop, Bordeaux , France (November 18-20, 2010); SMAI Cérémonie des Grand Prix, Paris, France (November 25, 2010);

Graph searching track of the 24th European Conference on Operational Research (EURO'10), Lisbon, Portugal (July 11-14, 2010); LIRMM seminar, Montpellier, France (November 4, 2010);

Invited talk at the VSIM Seminar (Carleton University)

Workshop on Future Internet, Mannheim, Germany (March 2010); European Forum for Innovation, Trento, Italy, June 2010; Workshop PARADISO, Brussels, Belgium (November 2010); Workshop on New ways of doing research which address societal challenges, Brussels, Belgium (November 2010);

Workshop Green Networking, Seminar of the INRIA-Alcatel Lucent Bell common lab, Villarceau, France (March 19, 2010); Panel Session Energy-aware, Power-aware, and Green Computing for Large Distributed Systems and Applications, International Conference on High Performance Computing &Simulation (HPCS'10), Caen, France (June 28-July 2, 2010);

International Conference on Graph Theory, Combinatorics and Applications (ICGTCA), Zhejiang Normal University, Jinhua, China (Oct. 29 - Nov. 2, 2010); Centenary of Celina + Frederic (C+C=100), University Joseph Fourier, Grenoble (September 16-17, 2010);

Presentation for the Seminar on sustainable development at INRIA Sophia Antipolis, in videoconference for 7 INRIA sites (March 22, 2010);

Graph searching track of the 24th European Conference on Operational Research (EURO'10), Lisbon, Portugal (July 11-14, 2010).

IST FET AEOLUS meeting, Athens, Greece (January 20-21, 2010).

Attended by J-C. Bermond and D. Coudert;

IST FET AEOLUS final meeting, München, Germany (February 22-24, 2010).

Attended by J-C. Bermond and F. Giroire;

Kick off meeting of ANR Blanc AGAPE, LIFO, Orléans (January 7-8, 2010).

Attended by N. Cohen (speaker), D. Coudert, F. Havet (speaker), D. Mazauric, N. Nisse, L. Sampaio, M. Syska (speaker);

Plenary meeting of Alcatel-Lucent/INRIA Joint lab, Villarceaux, France (March 18-19, 2010). Attended by D. Coudert, P. Giabbanelli, F. Giroire;

*Journée du pôle COMRED*, Sophia Antipolis, France
(March 1st, 2010).

Attended by most of the Mascotte members (speakers: F. Havet, J. Ribault);

3rd Czech-Sloveno-French Workshop on Graph coloring, Puyloubier, France (August 30-September 3, 2010). Attended by N. Cohen, F. Havet, L. Sampaio;

Workshop on dynamic compact routing, Alcatel-Lucent Bell labs, Antwerpeen, Belgium (May 5-6, 2010). Attended by D. Coudert, L. Hogie, A. Lancin;

Closing meeting of the DCR project, Paris, France (December 6, 2010).

Attended by D. Coudert, L. Hogie, A. Lancin, N. Nisse;

Meeting of sub-project 4 of ANR Verso ECOSCELLS, Sophia Antipolis, France (January 15, 2010). Attended by D. Coudert, N. Vieira Nepomuceno, I. Tahiri;

Kick-off meeting of the FP7 STREP EULER project, Antwerp, Belgium (October 6-8, 2010).

Attended by D. Coudert, A. Lancin, N. Nisse;

Workshop on FET Flagships, Brussels, Belgium (June 2010).

Attended by A. Ferreira;

FIRE week: future internet research and innovation, Barcelona, Spain (June 30, July 1, 2010).

Attended by D. Coudert;

1st
*GRATEL meeting*, Paris, France (January 20,
2010).

Attended by N. Cohen, F. Havet, L. Sampaio;

Meeting of AdR HiMa, Alcatel-Lucent/INRIA Joint lab, Villarceaux, France (March 17, 2010).

Attended by D. Coudert, P. Giabbanelli, F. Giroire;

Information and Communication Technologies: Digitally driven (ICT 2010), Brussels, Belgium (September 27-29, 2010). Attended by D. Coudert; A. Ferreira;

Mascotte project annual seminar, Rocquebrune Cap-Martin, France (May 3-4, 2010).

Attended by most of the MASCOTTE members;

9th
*Journées du Pôle ResCom du GDR ASR*, Lyon, France
(November 25-26, 2010).

Attended by D. Coudert, A. Lancin, N. Vieira Nepomuceno (speaker), I. Tahiri;

Final meeting of ANR SPREADS, Université Paris 6, Paris, France (December 13th, 2010).

Attended By O. Dalle, F. Giroire;

Interrelation between Technological, Social and Economic Trends, Brussels, Belgium (June 2010), and final workshop, Brussels, Belgium (November 2010).

Attended by A. Ferreira.

*8th French Combinatorial Conference*, Orsay,
France (June 28th - July 2nd, 2010).

Attended by J. Araújo, J-C. Bermond, N. Nisse (speaker), L. Sampaio;

*12th rencontres francophones sur les aspects
algorithmiques des télécommunications*, Belle Dune,
France (June 16-19, 2010).

Attended by J. Araújo, D. Coudert, A. Ferreira, P. Giabbanelli (speaker), F. Giroire, N. Vieira Nepomuceno, J. Monteiro (speaker), J. Moulierac, N. Nisse (speaker) and I. Tahiri;

*Bordeaux Graph workshop*, Bordeaux, France
(November 18-20, 2010).

Attended by J-C Bermond, F.Havet;

*Workshop on Complex and Communication Networks*,
Miami, USA (December 6-10, 2010).

Attended by Philippe Giabbanelli (speaker);

*2nd Workshop on Complex Networks*, Rio de
Janeiro, Brazil (October 13-15, 2010).

Attended by Philippe Giabbanelli (speaker);

*24th European Conference on Operational
Research*(EURO XXIV), Lisbon, Portugal (July 11-14,
2010).

Attended by D. Coudert (speaker), N. Nisse (speaker);

Trento, Italy (June 2010).

Attended by A. Ferreira;

*5th International Conference on FUN with
Algorithms*, Ischia Island, Italy (June 2-4,
2010).

Attended by D. Mazauric (speaker);

*3rd International Conference on Data Management in
Grid and P2P Systems*, Bilbao, Spain (September 1-2,
2010).

Attended by J. Monteiro (speaker);

*IEEE GLOBal COMmunications Conference*, Miami,
United States, (December 6-10, 2010).

Attended by F. Giroire (speaker);

*37th International Colloquium on Automata, Languages
and Programming*, Bordeaux, France (July 5-12,
2010).

Attended by D. Coudert, N. Nisse;

*11es Journées Doctorales en Informatique et
Réseaux*, Sophia Antipolis, France (March 24-26,
2010).

Attended by most of the members of MASCOTTE;

*12th Journées Graphes et Algorithmes*, Marseille,
France (November 8-10, 2010).

Attended by J. Araújo (speaker), J-C. Bermond, N. Cohen (speaker), D. Coudert, F. Havet, A. Lancin, D. Mazauric (speaker), J. Moulierac, N. Nisse and L. Sampaio (speaker);

Symposium "The future of sectoral innovation", Brussels, Belgium (April 2010).

Attended by A. Ferreira;

*4th conference on Optimal Discrete Structures and
Algorithms*, Rostock, Germany (September 13-15,
2010).

Attended by M. Toko Worou (speaker);

*3d international workshop on OMNeT++*, Malaga,
Spain (March, 15-19, 2010).

Attended by O. Dalle, J-C. Maureira (speaker and publicity chair), J. Ribault;

*29th Annual ACM Symposium on Principles of
Distributed Computing*, Zurich, Switzerland (July
25-28, 2010).

Attended by J. Burman (speaker);

Workshop on Ehtics and Digital Sciences, Brussels, Belgium (September 2010).

Attended by A. Ferreira;

New York, USA (June 14-18, 2010).

Attended by D. Mazauric (speaker);

3rd International ICST Conference on
*Simulation Tools and Techniques*, Malaga, Spain
(March 15-19, 2010).

Attended by O. Dalle, J-C. Maureira, J. Ribault (speaker);

*1st workshop Toward Evolutive Routing Algorithms for
scale-free/internet-like NETworks*, co-located with
ICALP'10, Bordeaux, France (July 5, 2010).

Attended by D. Coudert, N. Nisse (organizer);

Algorithmique, combinatoire du texte et applications en bio-informatique, Montpellier, France (January 25-26, 2010).

Attended by M. Toko Worou (speaker).

XV
*Escuela Latino Americana de Verano en Investigatión
Operativa*, Pacoti, Brazil (August 2-6, 2010).
Attended by J. Araujo;

7th
*Journées Combinatoire et Algorithmes du Littoral
Méditerranéen*, Montpellier, France (June 25, 2010).
Attended by J. Araujo, L. Sampaio, N. Cohen, J. Dousse,
H. Hsu, A. K. Maia de Oliveira and I. Tahiri;

*École ResCom 2010*, Giens, France (June 13-18,
2010).

Attended by J-C. Maureira;

*First Montreal Spring School in Graph Theory*,
Montreal, Canada (May 2010).

Attended by N. Cohen and N. Nisse.

F. Havet presented the stand "A quoi servent les mathématiques" at Rians, France (October 21-24, 2010);

Michel Syska has presented "MASCOPT
une boite à outils de manipulation de graphe",
Polytech?Nice-Sophia (November 26, 2010)
http://

J-C. Bermond and D. Mazauric have presented "les métiers de la recherche" at the Conferences 2GT and 1S STI STL in the Lycée de La rouvière Toulon (April 29, 2010);

F. Havet gave the lecture: "Les problèmes mathématiques à travers les âges", Rians, France (December 10, 2010).

*Algorithmique et optimisation dans les réseaux de
télécommunications*, March 2010;

*Contribution à l'algorithmique des réseaux de
télécommunications*, March 2010;

*Modeling and Analysis of Reliable Peer-to-Peer
Storage Systems*, November 16 2010;

*Network optimization for wireless microwave
backhaul*, December 17 2010;

*Dynamic network routing*, since December
2009.

*Allocation de fréquences et coloration des
L-graphes*, since October 2008;

*Internet on Rails*, since February 2008,
defense planned January 21, 2011;

*Conception et analyse d'algorithmes distribués
d'ordonnancement dans les réseaux sans-fil*, since
October 2008;

*Systèmes pair-à-pair de partage de données*,
since November 2010;

*Routing reconfiguration in WDM networks*, since
November 2010;

*Modélisation et simulation à événements discrets à
base de composants Fractal*, since January
2008;

*Algorithmic aspects of graph colorings*, since
November 2009;

*Optimisation dans les réseaux de collecte IP sans
fils*, since November 2009;

*Outils algorithmiques pour la détection des
communautés*, since November 2009.

Ph.D. committee of Fen Zhou (IRISA, Rennes, France, Sepember 6, 2010), and Napoleão Vieira Nepomuceno (UNS, Nice, France, December 17, 2010);

Ph.D. committee of Julian Monteiro, (UNS, Nice, France, November 16, 2010) "Modeling and Analysis of Reliable Peer-to-Peer Storage Systems", (O. Dalle and S. Perennes co-directors);

PhD M. Chen, University of Bordeaux 1, November 17, 2010, (external referee); HDR M. Montassier, University of Bordeaux 1, November 17, 2010, (external referee); PhD A. Silva, University Joseph Fourier, Grenoble, November 24, 2010, (external referee).

supervised the internship of Henry Wei Cheng Hsu (École Polytechnique, Paris, France) on the pathwidth of outerplanar graphs, April-August 2010 (4 months 1/2).

supervised the internship of Sonia Belhareth (ENIT Tunis, Tunisia) on Routing reconfiguration in WDM networks, February-May 2010 (4 months).

supervised the internship of Inza Bamba (UBINET), March-August 2010 (6 months).

supervised the internship of Ana Karolina Maia de Oliveira (Universidade Federal do Ceará, Fortaleza, Brazil), April-June 2010 (3 months).

supervised the internship of Jehanne Dousse (ENS Lyon), April-June 2010 (3 months).

supervised the internship of Remigiusz Modrzejewski (UBINET), March-August 2010 (6 months).

supervisor of Yoann Bertrand, Apprenti en Licence Professionnelle Systèmes Informatiques et Logiciels (IUT of Nice - Côte d'azur) on Administration du Réseau Expérimental du Projet MASCOTTE (September 2009-August 2010, 1 year).

Mascottehas widely
contributed to the launching and success of the stram UBINET
of the master IFI: a new international master of science at
University of Nice Sophia Antipolis (
http://

At the graduate level, members of Mascotteare also involved in teaching in other Masters like the master MDFI of University of Marseille or in the 3rd year of engineering schools.

The members of Mascotteare heavily involved in teaching activities at undergraduate levels (Licence, IUT, Master 1, ENS program, Engineering Schools like Polytech'Nice). Some members are also involved in administrative duties related to teaching. For example, M. Syska is director of the Licence LP SIL degree at IUT. The teaching is carried out by members of the University as part of their teaching duties, and for INRIA CNRS or Ph.D.'s as extra work.

Altogether that represents more than 1000 hours per year.

The members of Mascottealso supervise several student projects and internships at all levels (Master 1 and 2, Engineering Schools).