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

The structure and dynamics of multilayer networks

Tables of integrals

Many ``real-world'' networks are clearly defined while most ``social'' networks are to some extent subjective. Indeed, the accuracy of empirically-determined social networks is a question of some concern because individuals may have distinct perceptions of what constitutes a social link. One unambiguous type of connection is sexual contact. Here we analyze data on the sexual behavior of a random sample of individuals, and find that the cumulative distributions of the number of sexual partners during the twelve months prior to the survey decays as a power law with similar exponents $\alpha \approx 2.4$ for females and males. The scale-free nature of the web of human sexual contacts suggests that strategic interventions aimed at preventing the spread of sexually-transmitted diseases may be the most efficient approach.

The Web of Human Sexual Contacts

Fast Fourier Transform

Synchronization of a unified chaotic system and the application in secure communication

Adaptive feedback synchronization of a unified chaotic system

Many existing papers investigated the geometric features, control and synchronization of complex dynamical networks provided with certain topology. However, the exact topology of a network is sometimes unknown or uncertain. Based on LaSalle’s invariance principle, we propose an adaptive feedback technique to identify the exact topology of a weighted general complex dynamical network model with time-varying coupling delay. By receiving the network nodes evolution, the topology of such a kind of network with identical or different nodes, or even with varying topology can be monitored. In comparison with previous methods, time delay is taken into account in this simple, analytical and systematic synchronization-based technique. Particularly, the weight configuration matrix is not necessarily symmetric or irreducible, and the inner-coupling matrix need not be symmetric. Illustrative simulations are provided to verify the correctness and effectiveness of the proposed scheme.

Synchronization-based topology identification of weighted general complex dynamical networks with time-varying coupling delay

In this paper, the problem of generalized outer synchronization between two completely different complex dynamical networks is investigated. With a nonlinear control scheme, a sufficient criterion for this generalized outer synchronization is derived based on Barbalat’s lemma. Two corollaries are also obtained, which contains the situations studied in two lately published papers as special cases. Numerical simulations further demonstrate the feasibility and effectiveness of the theoretical results.

/pdf/generalized-outer-synchronization-between-complex-dynamical-qx62ofy7ih.pdf

Generalized outer synchronization between complex dynamical networks.

This brief presents some rules and properties about synchronizability of duplex networks composed of two networks interconnected by two links. For a specific duplex network composed of two star networks, analytical expressions containing the largest and smallest nonzero eigenvalues of the (weighted) Laplacian matrix, the interlink weight, and the network size are given for three different interlayer connection patterns. It is shown that connection patterns have great influence on the ability of the duplex system to synchronize, and connecting high-degree nodes is the most effective way to achieve synchronization, while connecting low-degree nodes is the least. Numerical examples are also provided to verify the effectiveness of theoretical analysis. This work sheds new light on understanding synchronizability of groups of interconnected networks or networks of networks (NONs). Particularly, in the design of circuit networks such as power grids, the findings can facilitate engineers with optimal selections of interconnection patterns and parameter assignments, in terms of optimizing the stability of desired synchronous states and minimizing control cost.

Xiaoqun Wu

Papers

Synchronization of a unified chaotic system and the application in secure communication

Adaptive feedback synchronization of a unified chaotic system

Synchronization-based topology identification of weighted general complex dynamical networks with time-varying coupling delay

Generalized outer synchronization between complex dynamical networks.

Synchronizability of Duplex Networks