• Home
  • Stephane Grumbach
Stephane Grumbach

Stephane Grumbach
INRIA, National Institute for Research in Computer Science and Control

About

140
Publications
6,457
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
2,716
Citations
Citations since 2016
23 Research Items
456 Citations
2016201720182019202020212022020406080
2016201720182019202020212022020406080
2016201720182019202020212022020406080
2016201720182019202020212022020406080
Introduction
Skills and Expertise

Publications

Publications (140)
Article
Full-text available
“Digital sovereignty” has become a buzzword in digital policies. Contrary to the imaginary of digital transformation as preceding an era of limitless global networking in the 1990s, approaches to state regulation and delimitation of data flows as well as programmes for national digital infrastructures are justified with calls for digital sovereignt...
Article
Full-text available
Non-technical summary Our time seems to be trapped in a paradox. On the one hand, the capacity to master information has tremendously increased, but on the other hand the capacity to use the knowledge humanity produces seems at stake. There is a gap between our capacity to know and our capacity to act. We attempt to better understand that situation...
Article
Full-text available
Human societies rely on rules to function, curbing the interests of individuals in favor of the interests of the population. A review of recent progress in biology and digital sciences suggests that such strategies might be universal: many living and technological systems favor the interests of the population to the detriment of individuals, at all...
Chapter
This chapter examines the factors that led to the advent of the very powerful intermediation services that web platforms provide. The new intermediaries threaten professions that were thought to be firmly established: advertising, newspapers, taxis, hotels, etc. The chapter analyzes the disruption of trade that plays in favor of web operators. Inte...
Article
Full-text available
Web tracking plays a crucial role in the Web ecosystem. It relies on third-party tracking actors collecting user information that are used for various applications such as advertisement and analytics, etc. With the massive growth of the Internet, understanding the geography of tracking is of strategic importance. The goal of this paper is to propos...
Article
The flows of people, goods and capital, which have considerably increased in recent history, are leading to crises (e.g., migrants, tax evasion, food safety) which reveal the failure to control them. Much less visible, and not yet included in economic measurements, data flows have increased exponentially in the last two decades, with the digitisati...
Article
The proliferation of digital technologies increases the density of the communication network among all actors, devices, humans and institutions. It contributes to the emergence of new modes of organization, facilitating direct exchanges between participants and, potentially, frugal use of resources. This profound transformation concurs with the end...
Article
Although many studies have been carried out on the way the law understands and deals with the digital revolution and particularly the Internet and, to a lesser extent, on the relationship between geography and the law, to our knowledge the "datasphere" as creating a new "space" for the law has received little attention. This contribution, written a...
Conference Paper
Most online lotteries today fail to ensure the verifiability of the random process and rely on a trusted third party. This issue has received little attention since the emergence of distributed protocols like Bitcoin that demonstrated the potential of protocols with no trusted third party. We argue that the security requirements of online lotteries...
Conference Paper
Aggregation of values that need to be kept confidential while guaranteeing the robustness of the process and the correctness of the result is required in an increasing number of applications. We propose an aggregation algorithm, which supports a large spectrum of potential applications including complex voting protocols. It relies on the distribute...
Conference Paper
While online services emerge in all areas of life, the voting procedure in many democracies remains paper-based as the security of current online voting technology is highly disputed. We address the issue of trustworthy online voting protocols and recall therefore their security concepts with its trust assumptions. Inspired by the Bitcoin protocol,...
Article
Algorithmic Intermediation, why now? The adoption of digital technologies increases the density of the communication network between humans, machines and institutions. The digital contributes to the emergence of new temporalities and new modes of organization, facilitating direct exchanges between actors and a potentially frugal use of resources. T...
Article
Full-text available
La révolution numérique transforme le monde. Alors que les nouveaux services sont largement plébiscités par la population, le système politique rappelle réguliè-rement l'illégalité des innovations disruptives pour l'équilibre social. Les données, matière première des rouages du numérique, contribuent à dessiner de nouveaux rapports de pouvoir entre...
Article
Full-text available
Intermediation is the action to match two types of actors (users, clients, services, etc.) in a world with incomplete information, where the matching would have been rather difficult without intermediaries. We show the increasing role of on-line intermediation platforms in the economy, and their growing respon-sibility for ensuring global security...
Article
Full-text available
Online social networks have been adopted by a large part of the population, and have become in few years essential communication means and a source of information for journalists. Nevertheless, these networks have some drawbacks that make people reluctant to use them, such as the impossibility to claim for ownership of data and to avoid commercial...
Article
Social Data, the Most Coveted of Object Personal data play in the undergoing social revolution a role, which is as important for the economy as it is fundamental for the political choices. As their production increases exponentially, the exploitation of these data in the last decade has lead to a growth of the Internet giants, such as Google or Fac...
Article
Personal data play in the undergoing social revolution a role, which is as important for the economy as it is fundamental for the political choices. As their production increases exponentially, the exploitation of these data in the last decade has lead to a growth of the Internet giants, such as Google or Facebook, unprecedented in the history of i...
Article
Nous proposons une approche basée sur les réseaux pair à pair pour distribuer de manière transparente des applications définies par des requêtes sur une base de données centralisée. Nous considérons des applications pour lesquelles les utilisateurs ont accès à des vues qui contiennent des fragments horizontaux des données qui les intéressent. Les r...
Article
Applications running over decentralized systems, distribute their computation on nodes/agents, which exchange data and services through messages. In many cases, the provenance of the data or service is not relevant, and applications can be optimized by choosing the most efficient solution to obtain them. We introduce a framework which allows messag...
Conference Paper
Full-text available
Microblogs, although extremely peculiar pieces of data, constitute a very rich source of information, which has been widely exploited recently, thanks to the liberal access Twitter offers through its API. Nevertheless, computing relevant answers to general queries is still a very challenging task. We propose a new engine, the Twittering Machine, wh...
Article
This paper introduces the syntax and the distributed fixpoint semantics of a rule-based declarative language, Netlog. The strongly well-behaved programs were defined, which were proven insensitive to bounded message loss.
Article
An UBIQUEST system provides a high level programming abstraction for rapid prototyping of heterogeneous and distributed applications in a dynamic environment. Such a system is perceived as a distributed database and the applications interact through declarative queries including declarative networking programs (e.g. routing) and/or specific data-or...
Article
The paper introduces our vision for rapid prototyping of heterogeneous and distributed applications. It abstracts a network as a large distributed database providing a unified view of "objects" handled in networks and applications. The applications interact through declarative queries including declarative networking programs (e.g. routing) and/or...
Article
Full-text available
We present the QuestMonitor system, which al-lows to visualize dynamic networks, and monitor the execu-tion of protocols written in a data centric and declarative language: Netlog. This language allows to write protocols, which are two orders of magnitude shorter than imperative programs. Nevertheless, their behavior is sometimes tricky to understa...
Article
Full-text available
R&D and innovation have become much more strategic than ever before for the growth of China as well as for its global societal upgrade. The Chinese authorities have designed an innovation strategy to face new economic and social challenges. The first part of the paper is focused on the emergence of the policy, in the 2006-2020 Plan for S&T, with a...
Article
Full-text available
We present an approach based on peer-to-peer overlays which allows to distribute seamlessly data centric applications defined by queries over a centralized database. We consider applications in which the users have access to views, which contain horizontal fragments of the data of interest to them. The peer-to-peer overlays are defined by simple de...
Conference Paper
Full-text available
Data centric languages, such as recursive rule based languages, have been proposed to program distributed applications over networks. They simplify greatly the code, while still admitting efficient distributed execution. We show that they also provide a promising approach to the verification of distributed protocols, thanks to their data centric or...
Article
Full-text available
Declarative languages, such as recursive rule based languages, have been proposed to program distributed applications over networks. It has been shown that they simplify greatly the code, while still offering efficient distributed execution. In this report, we show that moreover they provide a promising approach to the verification of distributed p...
Article
In-network query processing on wireless sensor networks handles queries in a distributed manner by decomposing them into subqueries, which are evaluated on groups of hosts (nodes) on the network. Reducing the amount of nodes to which (sub)queries as well as data are sent in the network is essential to reduce the communication cost, crucial for rest...
Article
In this paper, we report on our experiment with the deployment of a virtual machine, Netquest, which evaluates protocols written in a declarative language, over iMote devices. Netquest offers a new programming model for sensor networks with a high level of abstraction. Protocols and applications can be written in a simple rule-based language, which...
Article
Full-text available
Declarative languages, such as recursive rule based languages, have been proposed to program distributed applications over networks.It has been shown that they simplify greatly the code, while still offering efficient distributed execution. In this paper, we show that moreover they provide a promising approach to the verification of distributed pro...
Conference Paper
The tree decomposition of graphs is a fundamental algorithmic tool. It has been shown that difficult problems, such as some NP-complete ones, can be solved efficiently over classes of graphs of bounded tree-width. We consider in this paper the distributed construction of the tree decompositions of network topology graphs. We propose algorithms to d...
Conference Paper
Full-text available
We propose a rule-based language, Netlog, to express distributed applications such as communication protocols or P2P applications in a declarative manner. The language extends Datalog with communication primitives, as well as aggregation and non-deterministic constructs, standard in network applications. Our contribution is twofold. First we define...
Conference Paper
Full-text available
First-order logic is known to have limited expressive power over finite structures. It enjoys in particular the locality property, which states that first-order formulae cannot have a global view of a structure. This limitation ensures their low sequential computational complexity. We show that the locality impacts as well on their distributed comp...
Article
Full-text available
Logical formalisms such as first-order logic (FO) and fixpoint logic (FP) are well suited to express in a declarative manner fundamental graph functionalities required in distributed systems. We show that these logics constitute good abstractions for programming distributed systems as a whole, since they can be evaluated in a fully distributed mann...
Conference Paper
Because of irreversibility of movements, motion planning on directed graphs is much more intricate than that on graphs. Recently we showed that the feasibility of motion planning on acyclic and strongly connected directed graphs can be decided in time O(nm) (n,m are respectively the number of vertices and arcs of the directed graph), but left the f...
Article
Full-text available
We consider distributed model-checking of Monadic Second-Order logic (MSO) on graphs which constitute the topology of communication networks. The graph is thus both the structure being checked and the system on which the distributed computation is performed. We prove that MSO can be distributively model-checked with only a constant number of messag...
Article
Full-text available
First-order logic is known to have limited expressive power over finite structures. It enjoys in particular the locality property, which states that first-order formulae cannot have a global view of a structure. This limitation ensures on their low sequential computational complexity. We show that the locality impacts as well on their distributed c...
Article
Motion planning is a fundamental problem of robotics with applications in many areas of computer science and beyond. Its restriction to graphs has been investigated in the literature for it allows to concentrate on the combinatorial problem abstracting from geometric considerations. In this paper, we consider motion planning over directed graphs, w...
Article
Full-text available
One of the barriers to the implementation and deployment of pervasive applications is the lack of a programming abstraction for ubiquitous computing. We propose a system (i) that supports a declar-ative programming language, Netlog, well suited to rapid prototyping of distributed applications, (ii) which relies on an embedded DBMS, which facilitate...
Conference Paper
Full-text available
The use of declarative query languages has been proposed recently to express communication protocols. This approach, known as declarative networking, is very promising since it results in very simple programs, which are very easy to use. In this paper, we pursue this approach and show how to express the FISCO protocol using less than 40 simple decl...
Chapter
We study the issue of adding a recursion operator to constraint query languages for linear spatial databases. We introduce a language with a bounded inflationary fixpoint operator which is closed and captures the set of polynomial time computable queries over linear constraint databases. This is the first logical characterization of the class of PT...
Conference Paper
Advances in wireless sensor networks and positioning technologies enable traffic management (e.g. routing traf- fic) that uses real-time data monitored by GPS-enabled cars. Location management has become an enabling tech- nology in such application. The location modeling and tra- jectory prediction of moving objects are the fundamental components o...
Chapter
We study languages for manipulating partially ordered structures with duplicates (e.g. trees, lists). As a general framework, we consider the pomset (partially ordered multiset) datatype. We introduce an algebra for pomsets, which generalizes traditional algebras for (nested) sets, bags and lists. This paper is motivated by the study of the impact...
Article
We introduce a first-order language with real polynomial arithmetic and aggregation operators (count, iterated sum and multiply), which is well suited for the definition of aggregate queries involving complex statistical functions. It offers a good trade-off between expressive power and complexity, with a tractable data complexity. Interestingly, s...
Chapter
The introduction of spatio-temporal information in database systems presents us with an important data modelling challenge: the design of data models general and powerful enough to handle conventional thematic data, purely temporal or spatial concepts and spatio-temporal concepts.
Article
This paper presents dedale, a spatial database system, which provides an abstract and non-specialized data model and query language for representating and manipulating geometric data in arbitrary dimension. dedale relies on a logical model based on linear constraints. The main features of the constraint model are: (1) a uniform representation of al...
Article
Full-text available
This paper addresses fundamental issues related to the modeling of geometric data embedded in high-dimensional spaces. This covers several application fields, including moving objects where trajectories are described in a three- or four-dimensional space, and digital elevation models (DEMs). We show that moving objects and DEMs are specific instanc...
Article
We consider the problem of rewriting queries using only materialized views. We first show that if the views subsume the query from the point of view of the information content, then the query can be rewritten using only the views, but the resulting query might be extremely inefficient. We then focus on aggregate views and queries over a single rela...
Article
Full-text available
Most spatial information systems are limited to a fixed dimension (generally 2) which is not extensible. On the other hand, the emerging paradigm of constraint databases allows the representation of data of arbitrary dimension, together with abstract query languages. The complexity of evaluating queries though might be costly if the dimension of th...
Conference Paper
Full-text available
The paper presents a logical data model for statistical data with an explicit modeling of metadata, which allows to perform automatic aggregation. The data are stored in standard relations from the relational model, while the metadata, defining the semantics of the relations, are represented by numerical dependencies which specify the way the summa...
Conference Paper
Data defined by interpolation is frequently found in new applications involving, for instance, geographical concepts, moving objects, and spatio-temporal data. This data leads to potentially infinite collections of items, (e.g. the elevation of any point in a map), whose definition is based on the association of a collection of samples with an inte...
Conference Paper
This chapter introduces DEDALE, one of the first implementations of a database system based on the linear constraint model. DEDALE is a long term project started in 1996 as a cooperation between the VERSO group at INRIA and the VERTIGO group at CNAM. DEDALE is intended to demonstrate the practical relevance of this model to handle geometric applica...
Conference Paper
After studying, in the previous chapter, the expressive power of constraint queries over finite databases, we now turn to results concerning the complexity and expressive power of constraint query languages over possibly infinite, finitely representable, databases.
Conference Paper
The chapter is organized as follows. We first present a brief comparison of spatial modeling and query processing techniques for both traditional spatial databases and for constraint databases. We show how available techniques that have been developed for spatial databases can be used in the context of constraint databases. We then focus on those a...
Conference Paper
Full-text available
We consider the problem of solving a large number of simple systems of constraints. This problem occurs in the context of databases with very large collections of data while the constraints are over a small number of variables. The methodology we develop is based on a hierarchical evaluation of the constraints which are first simplified, and replac...
Conference Paper
We consider the problem of rewriting queries using only materialized views. We first show that if the views subsume the query from the point of view of the information content, then the query can be rewritten using only the views, but the resulting query might be extremely inefficient. We then focus on aggregate views and queries over a single rela...
Article
Constraint Databases, Edité par G. Kuper, L. Libkin et J. Paradaens
Article
Data defined by interpolation is frequently found in new applications involving, for instance, geographical concepts, moving objects, and spatio-temporal data. This data leads to potentially infinite collections of items, (e.g. the elevation of any point in a map), whose definition is based on the association of a collection of samples with an inte...
Article
Full-text available
After the successful first International Workshop on Engineering Federated Database Systems (EFDBS'97) in Barcelona in June 1997 [CEH+ 97], the goal of this second workshop was to bring together researchers and practitioners ...
Conference Paper
Full-text available
We study the problem of rediscovering the schema of nested relations that have been encoded as strings for storage purposes. We consider various classes of encoding functions, and consider the mark-up encodings, which allow to find the schema without knowledge of the encoding function, under reasonable assumptions on the input data. Depending upon...
Conference Paper
One of the most important advantages of constraint databases is their ability to represent and to manipulate data in arbitrary dimension within a uniform framework. Although the complexity of querying such databases by standard means such as first-order queries has been shown to be tractable for reasonable constraints (e.g. polynomial), it depends...
Article
Full-text available
We study languages for manipulating partially ordered structures with duplicates (e.g. trees, lists). As a general framework, we consider the pomset (partially ordered multiset) datatype. We introduce an algebra for pomsets, which generalizes traditional algebras for (nested) sets, bags and lists. This paper is motivated by the study of the impact...
Conference Paper
Full-text available
We introduce a first-order language with real polynomial arithmetic and aggregation operators (count, iterated sum and multiply), which is well suited for the definition of aggregate queries involving complex statistical functions. It offers a good trade-off between expressive power and complexity, with a tractable data complexity. Interestingly, s...
Conference Paper
Full-text available
This paper presents dedale, a spatial database system intended to overcome some limitations of current systems by providing an abstract and non-specialized data model and query language for the representation and manipulation of spatial objects. dedale relies on a logical model based on linear constraints, which generalizes the constraint database...
Conference Paper
Most spatial information systems are limited to a fixed dimension (generally 2) whichis not extensible. On the other hand, the emerging paradigm of constraint databasesallows the representation of data of arbitrary dimension. The complexity of evaluatingqueries though might be costly if the dimension of the objects is really arbitrary.In order to p...
Conference Paper
This paper presents a first prototype of a constraint database for spatial information, dedale. Implemented on top of the O2 DBMS, data is stored in an object-oriented framework, with spatial data represented using linear constraints over a dense domain. The query language is the standard OQL, with special functions for constraint solving and geome...
Conference Paper
Linear Constraints may constitute a good alternative to the widely used vector model for the representation of geometric objects. Linear Constraints are sets of inequalities of convex polygons and are simpler but more powerful than the relational model. Queries on thematic data and spatial data are expressed by operations on inequalities. This pape...
Article
We study infinite but finitely representable databases based on constraints, motivated by new database applications such as those involving spatio-temporal information. We introduce a general definition of finite representation, and define the concept of a query as a generalization of a query over relational databases. We investigate the theory of...
Article
Non-deterministic computation is not really computation, but the difference with real computation is blurred. We study in detail various levels of non-determinism in computations on non-deterministic Turing machines with polynomial bounds on the resources. Meanwhile, we consider numerous query languages, implicit logic, choice logic, order invarian...
Article
Non-deterministic computation is not really computation, but the difference with real computation is blurred. We study in detail various levels of non-determinism in computations on non-deterministic Turing machines with polynomial bounds on the resources. Meanwhile, we consider numerous query languages, implicit logic, choice logic, order invarian...
Article
In this paper, we study the expressive power and the complexity of first-order logic with arithmetic, as a query language over relational and constraint databases. We consider constraints over various domains (, , , and ), and with various arithmetical operations (⩽, +, ×, etc.).We first consider the data complexity of first-order queries. We prove...

Network

Cited By