David Chavalarias

School for Advanced Studies in the Social Sciences | EHESS · Centre d'analyse et de mathématique sociales (CAMS)

The advent of online social networks has led to the development of an abundant literature on the study of online social groups and their relationship to individuals' personalities as revealed by their textual productions. Social structures are inferred from a wide range of social interactions. Those interactions form complex -- sometimes multi-laye...

The COVID-19 pandemic that emerged in 2020 has highlighted the complex interplay between vaccine hesitancy and societal polarization. In this study, we analyse the dynamical polarization within a social network as well as the network properties before and after a vaccine was made available. Our results show that as the network evolves from a less s...

This research conducts an audit of Twitter’s recommender system, aiming to examine the disparities between users’ curated timelines and their subscription choices. Through the combined use of a browser extension and data collection via the Twitter API, our investigation reveals a high amplification of friends from the same community, a preference f...

As the last few years have seen an increase in online hostility and polarization both, we need to move beyond the fack-checking reflex or the praise for better moderation on social networking sites (SNS) and investigate their impact on social structures and social cohesion. In particular, the role of recommender systems deployed at large scale by d...

In April 2022, the French presidential election took place, and social media played a prominent role in it. By analyzing more than 150 million interactions on French Twitter, this study aims to provide evidence of coordinated behaviors from political parties. We find that extreme parties left and right, appear with a particular internal structure c...

Objective: to visualize the evolution of all registered COVID-19 vaccines trials STUDY DESIGN AND SETTING: as part of the living mapping of the COVID-NMA initiative, we identify biweekly all COVID-19 vaccine trials and automatically extract data from the EU clinical trials registry, ClinicalTrials.gov, IRCT and the WHO International Clinical Trial...

In 1751, Jean le Rond d'Alembert had a dream: "to make a genealogical or encyclopedic tree which will gather the various branches of knowledge together under a single point of view and will serve to indicate their origin and their relationships to one another". In this paper, we address the question identifying the branches of science by taking adv...

The ICT revolution has given birth to a world of digital traces. A wide number of knowledge-driven domains like science are daily fueled by unlimited flows of textual contents. In order to navigate across these growing constellations of words, interdisciplinary innovations are emerging at the crossroad between social and computational sciences. In...

The ICT revolution has given birth to a world of digital traces. A wide number of knowledgedriven domains like science are daily fueled by unlimited flows of textual contents. In order to navigate across these growing constellations of words, interdisciplinary innovations are emerging at the crossroad between social and computational sciences. In p...

Traceability is key to ensure food quality and safety from farm to fork, yet high implementation costs and the complexity of the food supply chain pose challenges to its operation. Here we propose a mobile-based bidirectional tracing system for food products that integrates graph data and peer-to-peer architecture. Our system allows data synchroniz...

Objectives: Researchers worldwide are actively engaging in research activities to search for preventive and therapeutic interventions against coronavirus disease 2019 (COVID-19). Our aim was to describe the planning of randomized controlled trials (RCTs) in terms of timing related to the course of the COVID-19 epidemic and research question evaluat...

Objectives Researchers worldwide are actively engaging in research activities to search for preventive and therapeutic interventions against coronavirus disease 2019 (COVID-19). Our aim was to describe the planning of randomized controlled trials (RCTs) in terms of timing related to the course of the COVID-19 epidemic and research question evaluate...

A few billion years have passed since the first life forms appeared. Since then, life has continued to forge complex associations between the different emergent levels of interconnection it forms. The advances of recent decades in molecular chemistry and theoretical biology, which have embraced complex systems approaches, now make it possible to co...

Un candidat dispose au moins de trois leviers pour gagner les voix des électeurs : convaincre de la pertinence de son programme et de ses idées ( positive campaigning ), convaincre de l’inadéquation ou du danger des programmes et des idées de ses adversaires ( negative campaigning ), et enfin, rendre familier son nom et celui de son parti auprès du...

Background Digital spaces, and in particular social networking sites, are becoming increasingly present and influential in the functioning of our democracies. In this paper, we propose an integrated methodology for the data collection, the reconstruction, the analysis and the visualization of the development of a country’s political landscape from...

Exhaustive data description and complementary analyses. Table of content: Text A: Main political events of the 2017 French presidential campaign,Text B: Data collection platform B.1 Collection focused on main political accounts (follow API),B.2 Collection focused on political terms (track API),B.3 List of the followed political figures (track and f...

La science est l'une des principales productions culturelles de nos sociétés et aussi l'un des premiers domaines d'activité a avoir vu sa production intégralement numérisée. Elle est donc un objet d'étude unique pour l'analyse et la compréhension des dynamiques culturelles (motifs d'innovations, dynamiques collectives, morphogenèse des réseaux soci...

En prenant appui sur l’expérience inédite du rapprochement de deux logiques d’enquête conçues comme antinomiques dans leurs raisonnements épistémologiques en sciences sociales, cet article explore les modalités d’articulation d’une approche mathématisée des grands réseaux, calculés à partir de flux du Web, et d’une approche socioinformatique des co...

We present a web-platform for building, customizing and exploring phylomemies, introduced by [Chavalarias+Cointet], for the synthetic representation of the evolution of scientific topics appearing in large document corpora. Phylomemies are built using computationally expensive data-centric workflows composed of complex text and graph mining steps....

There is an increasing pressure on scholars to publish to further or sustain a career in academia. Governments and funding agencies are greedy of indicators based on scientific production to measure science output. But what exactly do we know about the relation between publication levels and advances in science? How do social dynamics and norms int...

Importance The use and misuse of P values has generated extensive debates.Objective To evaluate in large scale the P values reported in the abstracts and full text of biomedical research articles over the past 25 years and determine how frequently statistical information is presented in ways other than P values.Design Automated text-mining analy...

http://tweetoscope.iscpif.fr Bien que le changement climatique constitue un enjeu sociétal majeur et mobilise la communauté scientifique internationale, la complexité du phénomène et de ses ramifications pose un réel défi de communication des recherches sur le sujet et de compréhension du grand public, voire dans certains cas, des décideurs. Comme...

Although information and communication technologies (ICT) have created hope for a shared pluralistic world, democratic principles are far from being respected in the public digital environment, and require a detailed knowledge of the laws by which they are governed. Von Foerster's conjecture is one of the early theoretical results that could help t...

Although ICT have created hope for a shared pluralistic world, democratic principles are far from being respected in the public digital environment, and require a detailed knowledge of the laws by which they are governed. Von Foerster's conjecture is one of the early theoretical results that could help to understand these laws. Although neglected s...

Nous distinguons trois visions de la complexité afin de clarifier les contours de la recherche dans ce domaine. Nous utilisons le démon de Laplace comme référence pour présenter ces visions. La vision 1 brise le rêve du démon de Laplace en identifiant des systèmes particuliers qui lui résistent en mathématiques, physique et informatique. La vision...

In this paper we propose a modern version of Laplace’s Demon that helps us unfold the notion of complexity into three visions revealing axes of difference and complementarity. The first vision concerns systems in mathematics, logics and physics which overthrow the illusion of past forms of predictability while opening the way to new concepts such a...

This paper presents the methodology and results of an exhaustive text-mining analysis performed on the subject "Dematerialization and Environment". Three main fields have been investigated: international academic publications (documents extracted from the Web of Science database during the period 1994-2013), French blog publications (pages crawled...

We introduce an automated method for the bottom-up reconstruction of the cognitive evolution of science, based on big-data issued from digital libraries, and modeled as lineage relationships between scientific fields. We refer to these dynamic structures as phylomemetic networks or phylomemies, by analogy with biological evolution; and we show that...

Details of the text-mining procedure. Description of the complete processing of textual data. It relies on classical linguistic processes, at the end of which sets of candidate noun phrases are defined. (PDF)

Study of the field size as an alternative coherence measure. Study of the patterns related to the yearly normalized size of scientific fields for comparison to patterns in density for the embryo dataset. (PDF)

Comparison with results from a different dataset. Presentation of a phylomemy reconstruction on a second dataset, performed in order to test the robustness of our results with respect to dataset variations and the quality of the terms list. This second data set, called “bio-networks”, is transdisciplinary. It comprises a biomedical corpus related t...

The conjecture of von Foerster describes the circular causal relationship between a whole (eg, a human community) and its elements (individual members). It establishes that when the relationship between individuals become more and more "rigid" (social influence is getting stronger) the behavior of the whole could appear, to the individual elements...

Executive Summary The new science of complex systems is providing radical new ways of understanding, modeling, predicting, managing the physical, biological, ecological, and social universe. Complex systems are characterised by emergent structures that occur in many domains and questions that apply across the domains in the modern world. Such integ...

Consultable sur Internet : http://pulseweb.veilledynamique.com/static/files/wp1.pdf

Many different types of bias have been described. Some biases may tend to coexist or be associated with specific research settings, fields, and types of studies. We aimed to map systematically the terminology of bias across biomedical research. We used advanced text-mining and clustering techniques to evaluate 17,265,924 items from PubMed (1958-200...

We propose a method to track emergent pedophilic keywords in P2P filenames

This second issue of the French Complex Systems Roadmap is the outcome of the Entretiens de Cargese 2008, an interdisciplinary brainstorming session organized over one week in 2008, jointly by RNSC, ISC-PIF and IXXI. It capitalizes on the first roadmap and gathers contributions of more than 70 scientists from major French institutions. The aim of t...

We are facing a real challenge when coping with the continuous acceleration of scientific production and the increasingly changing nature of science. In this article, we extend the classical framework of co-word analysis to the study of scientific landscape evolution. Capitalizing on formerly introduced science mapping methods with overlapping clus...

A “complex system” is in general any system comprised of a great number of heterogeneous entities, among which local interactions create multiple levels of collective structure and organization. Examples include natural systems ranging from bio-molecules and living cells to human social systems and the ecosphere, as well as sophisticated artificial...

Accurate and up-to-date knowledge of keywords entered by users who search or provide paedophile content is a key resource for filtering purposes and for monitoring by law enforcement institutions. However, such keywords are often hidden and may change frequently, and our current knowledge about them relies on manual inspection and field expertise....

2009 International Workshop on Complex Networks (CompleNet 2009)

Massive collections of scientific publications are now available on-line thanks to multiple public platforms. These databases usually cover large-scale scientific production over several decades and for a broad range of thematic areas. Today researchers are used to perform queries on these databases with keywords or combination of keywords in order...

We propose new innovative methods in order to reconstruct paradigmatic fields thanks to simple statistics over a scientific content database. We first define an asymmetric paradigmatic proximity between concepts which provides hierarchical structure over the set of concepts. We propose to implement overlapping categorization to describe paradigmati...

We propose a series of methods to represent the evolution of a field of science at different levels: namely micro, meso and macro levels. We use a previously introduced asymmetric measure of paradigmatic proximity between terms that enables us to extract structure from a large publications database. We apply our set of methods on a case study from...

Multi-agents modelers recurrently face the problem of the choice of their parameters' values while most of them are exogenous. In this paper we address the issue of endogenization of these parameters when it makes sense in a social learning perspective within the formalism of metamimetic games. We first show how its is possible to endogeneize the a...

Résumé Certains scientifiques, sociologues ou économistes en particulier, se sont récemment emparés du terme de cognition sociale utilisé en psychologie en lui donnant un second sens, à savoir, une cognition distribuée sur l’ensemble des individus composant une société. L’enjeu est alors de savoir « en quoi les aptitudes sociales humaines rendent c...

What are the principles underlying social differentiation? Socioeconomic models generally consider agents that pursue some particular ends a given, prior to their social activity. In this chapter we propose an alternative in the framework of metamimetic games. We claim that the distribution of ends in a population is the outcome of social interacti...

Certains scientiques, sociologues ou économistes en particulier, se sont récemment emparés du terme de cognition sociale utilisé en psychologie en lui donnant un second sens, à savoir, une cognition distribuée sur l'ensemble des individus composant une société. L'enjeu est alors de savoir " en quoi les aptitudes sociales humaines rendent compte du...

Imitation is fundamental in the understanding of social systems' dynamics. But the diversity of imitation rules employed by modelers proves that the modeling of mimetic processes cannot avoid the traditional problem of endogenization of all the choices, including the one of the mimetic rules. Starting from the remark that metacognition and human re...

Aggregated phenomena in social sciences and economics are highly dependent on the way individuals interact. To help understanding the interplay between socio-economic activities and underlying social networks, this paper studies a sequential prisoner's dilemma with binary choice. It proposes an analytical and computational insight about the role of...

We propose an analytical and computational insight about the role of endogenous networks in emergence and sustainability of cooperation and exhibits an alternative to the choice and refusal mechanism that is often proposed to explain cooperation.

Popper a rompu avec une tradition �pist�mologique ancienne en introduisant une dissym�trie entre v�rifiabilit� et r�futation. Cette conception a d'importantes r�percussions sur la mani�re d'envisager la croissance des connaissances scientifiques et l'activit� du chercheur. La v�rit�, qui avait pu �tre consid�r�e comme un but pour la recherche scien...

See also: http://www.chavalarias.com for online computational appendix

Quels sont les principes fondateurs de l'auto-organisation des sociétés humaines ? Produits d'une évolution culturelle rapide, qui a pris le pas sur l'évolution biologique, celles-ci réclament une approche par des formalismes radicalement différents de ceux utilisés généralement dans l'étude des autres sociétés animales. Concrètement, la modélisati...

The aim of this article is to address the question of the endogenization of mimetic processes in formal models of social systems. Starting from some studies about cognitive differences between humans and animals, we propose a formal framework which has the advantage to endogenise mimetic rules and give a comprehensive description of a heterogeneous...

The question of the emergence of cooperation in animal or human societies has focused the attention of the scientific community since the seminal work of Axelrod. We propose here a model which take into account the importance of local interactions in social networks and the possibility of selection of interactions at the individual level. Starting...

We propose a model of emergence of cooperation in evolutionary games that high-lights the role of network formation and eect of network structure. In line with empirical data, the model proposes a mechanism that explains the persistence of heterogeneous types (heterogeneity in rules for changing behavior) within a popu-lation, and in particular the...

We develop analytical and computational models to study the conditions for the stability of a population consisting of agents with heterogeneous preferences. The analytical models that utilize an indirect evolutionary approach show that the ability to detect others' types is critical for the evolution of reciprocal preferences. The computational mo...

We applied information geometry to treat the correlation beyond second order in network co-word analysis. We also defined the meta-level dynamics of these correlations based on all hierarchical combination of the variables, in order to encompass all possible relations. The result shows a rich variety of dynamics depending both on the order of corre...

Résumé Certains scientifiques, sociologues ou économistes en particulier, se sont récemment emparés du terme de cognition sociale utilisé en psychologie en lui donnant un second sens, à savoir, une cognition distribuée sur l'ensemble des individus composant une société. L'enjeu est alors de savoir "en quoi les aptitudes sociales humaines rendent co...

We propose new innovative methods in order to reconstruct paradigmatic fields thanks to simple statistics over a scientific content database. We first define an asymmetric paradigmatic proximity between concepts which provides hierarchical structure over the set of concepts. We propose to implement overlapping categoriza-tion to describe paradigmat...

Much attention has been given in the last several years to imitation processes for the modeling of social systems in economy as well as in anthropology, sociology and political science. But the diversity of mimetic rules employed by modelers proves that the introduction of mimetic processes into formal models cannot avoid the traditional problem of...

Much attention has been given in the last several years to the modeling of social systems in economy as well as in anthropology and political science. Among the phenomena considered as having a structuring power for social systems, imitation processes play a central role, completing and sometime competing with a more traditional economic approach b...