We will review some of the major results in random graphs and some of the more challenging open problems. We will cover algorithmic and structural questions. We will touch on newer models, including those related to the WWW.

Random graphs

/pdf/convex-analysisnoer-san-nojin-zhan-nituite-5dl2rbmoyr.pdf

Convex Analysisの二,三の進展について

We introduce a system for sensing complex social systems with data collected from 100 mobile phones over the course of 9 months. We demonstrate the ability to use standard Bluetooth-enabled mobile telephones to measure information access and use in different contexts, recognize social patterns in daily user activity, infer relationships, identify socially significant locations, and model organizational rhythms.

/pdf/reality-mining-sensing-complex-social-systems-2gf3rdnw3x.pdf

Reality mining: sensing complex social systems

National Institute of Standards and Technology における超伝導研究及び生活

A great variety of systems in nature, society and technology -- from the web of sexual contacts to the Internet, from the nervous system to power grids -- can be modeled as graphs of vertices coupled by edges The network structure, describing how the graph is wired, helps us understand, predict and optimize the behavior of dynamical systems In many cases, however, the edges are not continuously active As an example, in networks of communication via email, text messages, or phone calls, edges represent sequences of instantaneous or practically instantaneous contacts In some cases, edges are active for non-negligible periods of time: eg, the proximity patterns of inpatients at hospitals can be represented by a graph where an edge between two individuals is on throughout the time they are at the same ward Like network topology, the temporal structure of edge activations can affect dynamics of systems interacting through the network, from disease contagion on the network of patients to information diffusion over an e-mail network In this review, we present the emergent field of temporal networks, and discuss methods for analyzing topological and temporal structure and models for elucidating their relation to the behavior of dynamical systems In the light of traditional network theory, one can see this framework as moving the information of when things happen from the dynamical system on the network, to the network itself Since fundamental properties, such as the transitivity of edges, do not necessarily hold in temporal networks, many of these methods need to be quite different from those for static networks

Temporal Networks

Weak ties, introduced in the seminal paper by Granovetter [6], refer to people's relationships with acquaintances outside their social circle (i.e., acquaintances with which they interact infrequently). We show that weak ties play an important role on the dissemination of content updates over a mobile social network. From a practical perspective, weak ties can be used to design strategies for limiting the bandwidth usage on such a network, without severely impacting the speed with which the content is disseminated. Moreover, the importance of weak ties can be traced on the effect they have on the edge expansion of the social network. By identifying this relationship, we extend and validate earlier work [7], that characterizes the speed of content dissemination in terms of the network's edge expansion.

http://www.cs.columbia.edu/~augustin/pub/ioannidis09strength.pdf

On the strength of weak ties in mobile social networks

Why do biased algorithmic predictions arise, and what interventions can prevent them? We examine this topic with a field experiment about using machine learning to predict human capital. We randomly assign approximately 400 AI engineers to develop software under different experimental conditions to predict standardized test scores of OECD residents. We then assess the resulting predictive algorithms using the realized test performances, and through randomized audit-like manipulations of algorithmic inputs. We also used the diversity of our subject population to measure whether demographically non-traditional engineers were more likely to notice and reduce algorithmic bias, and whether algorithmic prediction errors are correlated within programmer demographic groups. This document describes our experimental design and motivation; the full results of our experiment are available at https://ssrn.com/abstract=3615404.

Biased Programmers? Or Biased Data? A Field Experiment in Operationalizing AI Ethics

http://www.cs.columbia.edu/~augustin/pub/he08performance.pdf

A performance evaluation of scalable live video streaming with nano data centers

The Internet is built around the assumption of contemporaneous end-to-end connectivity. This is at odds with what typically happens in mobile networking, where mobile devices move between islands of connectivity, having opportunity to transmit packets through their wireless interface or simply carrying the data toward a connectivity island. We propose Pocket Switched Networking, a communication paradigm which reflects the reality faced by the mobile user. Pocket Networking falls under DTN. We describe the challenges that this approach entails and provide evidence that it is feasible with today's technology.

Pocket Switched Networking: Challenges, Feasibility, and Implementation Issues

This study provides some new insights into the scalability of reliable group communication mechanisms using overlays. These mechanisms use individual TCP connections for packet transfers between end-systems. End-systems store incoming packets and forward them to downstream nodes using different unicast TCP connections. In this paper we assume that buffers in end-systems are large enough for the transfers. It is shown that the throughput of the reliable overlay group communication scales in the sense that for all multicast tree sizes and topologies, the group throughput is strictly positive under natural conditions. This is in contrast with the IP supported multicast paradigm where reliable protocols have vanishing throughput when the group size tends to infinity. The scalability of packet delay and buffer occupancy is then investigated. In the absence of additional control, the occupancy of the buffer and the latency in the end-systems explodes with time. It is then shown that proactive rate throttle mechanism implemented at the source leads to finite packet latency and buffer occupancy in any end-system of the network provided certain moment conditions are satisfied by cross traffic in the routers.

/pdf/scalability-of-reliable-group-communication-using-overlays-4b24cn32jv.pdf

Augustin Chaintreau

Papers

On the strength of weak ties in mobile social networks

Biased Programmers? Or Biased Data? A Field Experiment in Operationalizing AI Ethics

A performance evaluation of scalable live video streaming with nano data centers

Pocket Switched Networking: Challenges, Feasibility, and Implementation Issues

Scalability of reliable group communication using overlays