Inferring offline hierarchical ties from online social networks

Social networks can represent many different types of relationships between actors, some explicit and some implicit. For example, email communications between users may be represented explicitly in a network, while managerial relationships may not. In this paper we focus on analyzing explicit interactions among actors in order to detect hierarchical social relationships that may be implicit. We start by employing three well-known ranking-based methods, PageRank, Degree Centrality, and Rooted-PageRank (RPR) to infer such implicit relationships from interactions between actors. Then we propose two novel approaches which take into account the time-dimension of interactions in the process of detecting hierarchical ties. We experiment on two datasets, the Enron email dataset to infer manager-subordinate relationships from email exchanges, and a scientific publication co-authorship dataset to detect PhD advisor-advisee relationships from paper co-authorships. Our experiments show that time-based methods perform considerably better than ranking-based methods. In the Enron dataset, they detect 48% of manager-subordinate ties versus 32% found by Rooted-PageRank. Similarly, in co-author dataset, they detect 62% of advisor-advisee ties compared to only 39% by Rooted-PageRank

Who let the trolls out? Towards understanding state-sponsored trolls

Recent evidence has emerged linking coordinated campaigns by state-sponsored actors to manipulate public opinion on the Web. Campaigns revolving around major political events are enacted via mission-focused ?trolls." While trolls are involved in spreading disinformation on social media, there is little understanding of how they operate, what type of content they disseminate, how their strategies evolve over time, and how they influence the Web's in- formation ecosystem. In this paper, we begin to address this gap by analyzing 10M posts by 5.5K Twitter and Reddit users identified as Russian and Iranian state-sponsored trolls. We compare the behavior of each group of state-sponsored trolls with a focus on how their strategies change over time, the different campaigns they embark on, and differences between the trolls operated by Russia and Iran. Among other things, we find: 1) that Russian trolls were pro-Trump while Iranian trolls were anti-Trump; 2) evidence that campaigns undertaken by such actors are influenced by real-world events; and 3) that the behavior of such actors is not consistent over time, hence detection is not straightforward. Using Hawkes Processes, we quantify the influence these accounts have on pushing URLs on four platforms: Twitter, Reddit, 4chan's Politically Incorrect board (/pol/), and Gab. In general, Russian trolls were more influential and efficient in pushing URLs to all the other platforms with the exception of /pol/ where Iranians were more influential. Finally, we release our source code to ensure the reproducibility of our results and to encourage other researchers to work on understanding other emerging kinds of state-sponsored troll accounts on Twitter.https://arxiv.org/pdf/1811.03130.pdfAccepted manuscrip

Flexible resources allocation techniques: characteristics and modelling

At the interface between engineering, economics, social sciences and humanities, industrial engineering aims to provide answers to various sectors of business problems. One of these problems is the adjustment between the workload needed by the work to be realised and the availability of the company resources. The objective of this work is to help to find a methodology for the allocation of flexible human resources in industrial activities planning and scheduling. This model takes into account two levers of flexibility, one related to the working time modulation, and the other to the varieties of tasks that can be performed by a given resource (multi–skilled actor). On the one hand, multi–skilled actors will help to guide the various choices of the allocation to appreciate the impact of these choices on the tasks durations. On the other hand, the working time modulation that allows actors to have a work planning varying according to the workload which the company has to face

Making The Policy-Makers: Askesis, Or To Continuously Work On Oneself

This paper uses a Foucauldian discursive approach to shed light into how organisational actors are ‘made’ to act as strategists, incorporating into their work practices the demands and expectations of what it means to be a strategist in a specific context at a specific time. It draws on a Foucauldian understanding of governing and self formation to explore the ways in which actors work on themselves in order to act meaningfully as strategists. I argue that, rather than organisational identities being static or finished, organisational actors actively say and do things in their continual attempts to attain a more complete, acceptable and congruent identity. In contexts with high degrees of uncertainty and heavily power- and conflict-laden relationships, both discourses of how strategy is made and the practices involved in it can be seen as exercises (askesis) which strategists actively perform to better embrace their responsibility of rendering the future governable for others. The paper brings together the literatures on identity and on strategic practices to show the dialectic relationship between them

The Problem of Personal Income Tax Avoidance

The aim of this study is to analyze the concept of antiracism and explore what characterizes the kind of antiracism that the empirical examples presented in this study represent. The empirical examples are instances of what I call antiracist actors. They are rooted in civil society, but also have strong connections with the government through government funding. The empirical data has been gathered through both qualitative and quantitative methods, mainly in the form of a survey and interviews. In order to explore the antiracist actors I have focused on three themes: (1) the shapes and forms of racism, (2) antiracism as a phenomenon, and (3) antiracism as a social arena. Through these themes I have gathered information about how the antiracist actors interpret their activities and the context in which they are working. On the subject of the shapes and forms of racism, I establish that racism is a concept that is hard to define. The antiracist actors lack a common language regarding racism, which affects the antiracist rhetoric. Regarding antiracism as a phenomenon, I conclude that the antiracist strategies mainly consist of three components: (1) knowledge is used as a strategic instrument internally to strengthen the volunteers, (2) knowledge is spread externally to increase awareness of racism, and (3) the antiracist actors deconstruct racist beliefs when opposing racist opinions. Finally, I research antiracism as a social arena and study civil society and theories about social movements in order to explore organizational aspects of the antiracist actors. Using Alberto Meluccis’ social movement theories, there is some evidence to support the thesis that the antiracist actors could be defined as part of an antiracist movement. However, overall there are stronger arguments to suggest the opposite, mainly since the antiracist actors are not in opposition to one or more adversaries. Instead they work with target groups, sometimes targeting the general public, sometimes specific groups like children in a certain school. The main conclusion from my study in this respect is that the antiracist actors are part of what I call association-driven antiracism. The associationdriven antiracism is characterized by non-violent methods and the antiracist actors do not focus on racist adversaries, instead they work with target groups trying to influence them in an antiracist way. The association-driven antiracism secures its continuity through networks, since many activities are project-based and only last for a limited period of time. Also, the antiracist actors are not representatives of particular political parties, instead they gather around the question at hand, antiracism. The antiracist actors within the association-driven antiracism are in close collaboration with the government and partly finance their activities with government funding. This collaboration can be explained as a positive steering process, the rulers (the government) and those who are ruled (the antiracist actors) agree on an antiracist ideology and work in the same direction

Network dynamics of ongoing social relationships

Many recent large-scale studies of interaction networks have focused on networks of accumulated contacts. In this paper we explore social networks of ongoing relationships with an emphasis on dynamical aspects. We find a distribution of response times (times between consecutive contacts of different direction between two actors) that has a power-law shape over a large range. We also argue that the distribution of relationship duration (the time between the first and last contacts between actors) is exponentially decaying. Methods to reanalyze the data to compensate for the finite sampling time are proposed. We find that the degree distribution for networks of ongoing contacts fits better to a power-law than the degree distribution of the network of accumulated contacts do. We see that the clustering and assortative mixing coefficients are of the same order for networks of ongoing and accumulated contacts, and that the structural fluctuations of the former are rather large.Comment: to appear in Europhys. Let