共查询到20条相似文献,搜索用时 15 毫秒
1.
P. P. Li P. M. Hui 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,61(3):371-376
The dynamics of opinion formation based on a majority
rule model is studied in a network with the social hierarchical
structure as one of its limits. The exit probability is found to
change sensitively with the number of nodes in the system, but not
with the parameter of homophyly characterizing the network
structure. The consensus time is found to be a result of
non-trivial interplay between the network structure characterized
by the parameter of homophyly and the initial bias in opinion. For
unbiased initial opinion, a common consensus is easier to be
reached in a random network than a highly structured hierarchical
network and it follows the behavior of the length of shortest
paths. For biased initial opinion, a common consensus is easier
to be reached in a hierarchical network, as the local majority
opinion of the groups may take on the biased opinions and hence be
the same. 相似文献
2.
C. P. Herrero 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,56(1):71-79
Kinetically-grown self-avoiding walks have been studied on Watts-Strogatz
small-world networks, rewired from a two-dimensional square lattice.
The maximum length L of this kind of walks is limited in regular lattices
by an attrition effect, which gives finite values for its mean value
〈L 〉. For random networks, this mean attrition length
〈L 〉 scales as a power of the network size,
and diverges in the thermodynamic limit (system size N ↦∞).
For small-world networks, we find a behavior that interpolates between
those corresponding to regular lattices and randon networks, for rewiring
probability p ranging from 0 to 1.
For p < 1, the mean self-intersection and attrition length of
kinetically-grown walks are finite.
For p = 1, 〈L 〉 grows with system size as N1/2,
diverging in the thermodynamic limit. In this limit and
close to p = 1, the mean attrition length diverges as (1-p)-4.
Results of approximate probabilistic calculations agree well with
those derived from numerical simulations. 相似文献
3.
F. Fu L.-H. Liu L. Wang 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,56(4):367-372
We focus on the heterogeneity of social networks and its
role to the emergence of prevailing cooperators and sustainable
cooperation. The social networks are representative of the
interaction relationships between players and their encounters in
each round of games. We study an evolutionary Prisoner's Dilemma
game on a variant of Newman-Watts small-world network, whose
heterogeneity can be tuned by a parameter. It is found that
optimal cooperation level exists at some intermediate topological
heterogeneity for different temptations to defect. That is,
frequency of cooperators peaks at a certain specific value of
degree heterogeneity — neither the most heterogeneous case nor
the most homogeneous one would favor the cooperators. Besides, the
average degree of networks and the adopted update rule also affect
the cooperation level. 相似文献
4.
H. Zhao Z.-Y. Gao 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,57(1):95-101
In this paper, we investigate cascade defense and control
in scale free networks via navigation strategy. It is found
that with an appropriate parameter a, which is tunable in
controlling the effect of degree in the navigation strategy, one can
reduce the risk of cascade break down. By checking the distribution
of efficient betweenness centrality (EBC) and the average EBC
of vertices with degree k, the validity can be guaranteed. Despite
the advantage of cascade defense, the degree based navigation
strategy may also lead to lower network efficiency. To avoid this
disadvantage, we propose a new navigation strategy. Importantly and
interestingly, the new strategy can defend cascade break down
effectively even without reducing the network efficiency.
Distribution of the EBC and EBC-degree correlation of the new
strategy are also investigated to explain the effectiveness in
cascade defense. 相似文献
5.
S. Singh A. Samal V. Giri S. Krishna N. Raghuram S. Jain 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,57(1):75-80
Biological and social systems have been found to possess
a non-trivial underlying network structure of interacting
components. An important current question concerns the nature of the
evolutionary processes that have led to the observed structural
patterns dynamically. By comparing the metabolic networks of
evolutionarily closeby as well distant species, we present results
on the evolution of these networks over short as well as long time
scales. We observe that the amount of change in the reaction set of
a metabolite across different species is proportional to the degree
of the metabolite, thus providing empirical evidence for a
`proportionate change' mechanism. We find that this evolutionary
process is characterized by a power law with a universal exponent
that is independent of the pair of species compared. 相似文献
6.
S. Carmi Z. Wu E. López S. Havlin H. Eugene Stanley 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,57(2):165-174
We study the transport properties of model networks such as
scale-free and Erd?s-Rényi networks as well as a real
network. We consider few possibilities for the trnasport problem.
We start by studying the conductance G between two arbitrarily
chosen nodes where each link has the same unit resistance. Our
theoretical analysis for scale-free networks predicts a broad
range of values of G, with a power-law tail distribution
$\Phi_{\rm SF}(G)\sim G^{-g_G}$
, where gG=2λ-1, and
λ is the decay exponent for the scale-free network degree
distribution. The power-law tail in ΦSF(G) leads to
large values of G, thereby significantly improving the transport
in scale-free networks, compared to Erd?s-Rényi networks
where the tail of the conductivity distribution decays
exponentially. We develop a simple physical picture of the
transport to account for the results. The other model for
transport is the max-flow model, where conductance is defined
as the number of link-independent paths between the two nodes, and
find that a similar picture holds. The effects of distance on the
value of conductance are considered for both models, and some
differences emerge. We then extend our study to the case of
multiple sources ans sinks, where the transport is defined between two
groups of nodes. We find a fundamental difference between
the two forms of flow when considering the quality of the
transport with respect to the number of sources, and find an
optimal number of sources, or users, for the max-flow case. A
qualitative (and partially quantitative) explanation is also
given. 相似文献
7.
Evolution of canalizing Boolean networks 总被引:1,自引:0,他引:1
A. Szejka B. Drossel 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,56(4):373-380
Boolean networks with canalizing functions are used to model gene regulatory networks. In order to learn how such networks
may behave under evolutionary forces, we simulate the evolution of a single Boolean network by means of an adaptive walk,
which allows us to explore the fitness landscape. Mutations change the connections and the functions of the nodes. Our fitness
criterion is the robustness of the dynamical attractors against small perturbations. We find that with this fitness criterion
the global maximum is always reached and that there is a huge neutral space of 100% fitness. Furthermore, in spite of having
such a high degree of robustness, the evolved networks still share many features with “chaotic” networks. 相似文献
8.
N. Gupte B. K. Singh 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,50(1-2):227-230
We study network traffic dynamics in a two dimensional communication
network
with regular nodes and hubs.
If the network experiences heavy message traffic, congestion occurs due
to finite
capacity of the nodes. We discuss strategies to manipulate hub
capacity and hub
connections to relieve congestion and define a coefficient of
betweenness centrality
(CBC), a direct measure of network traffic, which is useful for
identifying hubs which
are most likely to cause congestion. The addition of assortative
connections to hubs
of high CBC relieves congestion very efficiently.
An erratum to this article is available at . 相似文献
9.
M. N. Kuperman M. Ballard F. Laguna 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,50(3):513-520
A model for a dynamic network consisting of changing
local interactions is presented in this work. While the network
maintains solely local connections, certain properties known only
to Small World Networks may be extracted due to the dynamic nature
of the model. At each time step the individuals are grouped into
clusters creating neighborhoods or domains of fully connected
agents. The boundaries of these domains change in time,
corresponding to a situation where the links between individuals
are dynamic only throughout the history of the network. A question
that we pose is whether our model, which maintains a local
structure such that diffusion calculations are possible, might
lead to analytic or conceptual advances for the much more
complicated case of diffusion on a static disordered network that
exhibits the same macroscopic properties as our dynamic
ordered network. To answer this, we compare certain properties
which characterize the dynamic domain network to those of a Small
World Network, and then analyze the diffusion coefficients for
three possible domain mutations. We close with a comparison and
confirmation of previous epidemiological work carried out on
networks. 相似文献
10.
G. Ghoshal M. E.J. Newman 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,58(2):175-184
We consider distributed networks, such as peer-to-peer networks, whose
structure can be manipulated by adjusting the rules by which vertices
enter and leave the network. We focus in particular on degree
distributions and show that, with some mild constraints, it is possible
by a suitable choice of rules to arrange for the network to have any
degree distribution we desire. We also describe a mechanism based on
biased random walks by which appropriate rules could be implemented in
practice. As an example application, we describe and simulate the
construction of a peer-to-peer network optimized to minimize search times
and bandwidth requirements. 相似文献
11.
M. Ludwig P. Abell 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,58(1):97-105
Social networks in communities, markets, and societies self-organise through the interactions of many individuals. In this
paper we use a well-known
mechanism of social interactions — the balance of sentiment in triadic
relations — to describe the development of social networks. Our model
contrasts with many existing network models, in that people not only
establish but also break up relations whilst the network evolves. The
procedure generates several interesting network features such as a variety
of degree distributions and degree correlations. The resulting network
converges under certain conditions to a steady critical state where temporal
disruptions in triangles follow a power-law distribution. 相似文献
12.
E. P. Borges D. O. Cajueiro R. F.S. Andrade 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,58(4):469-474
The objective of this study is to design a procedure to
characterize chaotic dynamical systems, in which they are
mapped onto a complex network. The nodes represent the regions of space
visited by the system, while the edges represent the transitions between
these regions. Parameters developed to quantify the properties of complex
networks, including those related to higher order neighbourhoods, are used
in the analysis. The methodology is tested on the logistic map, focusing
on the onset of chaos and chaotic regimes. The corresponding networks were
found to have distinct features that are associated with the particular
type of dynamics that generated them. 相似文献
13.
H. Lin C.-X. Wu 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,51(4):543-547
The congestion transition triggered by multiple walkers
walking along the shortest path on complex networks is numerically
investigated. These networks are composed of nodes that have a
finite capacity in analogy to the buffer memory of a computer. It is
found that a transition from free-flow phase to congestion phase
occurs at a critical walker density fc, which varies for
complex networks with different topological structures. The dynamic
pictures of congestion for networks with different topological
structures show that congestion on scale-free networks is a
percolation process of congestion clusters, while the dynamics of
congestion transition on non-scale-free networks is mainly a process
of nucleation. 相似文献
14.
J. M. Kumpula J. Saramäki K. Kaski J. Kertész 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,56(1):41-45
According to Fortunato and Barthélemy, modularity-based community detection
algorithms have a resolution threshold such that small communities in a large
network are invisible. Here we generalize their work and show that the q-state
Potts community detection method introduced by Reichardt and Bornholdt
also has a resolution threshold. The model contains a parameter by which this threshold can be tuned, but no a priori principle
is known to select the proper value.
Single global optimization criteria do not seem capable for detecting all
communities if their size distribution is broad. 相似文献
15.
Leslie Luthi 《Physica A》2008,387(4):955-966
Situations of conflict giving rise to social dilemmas are widespread in society. One way of studying these important phenomena is by using simplified models of individual behavior under conflicting situations such as evolutionary game theory. Starting from the observation that individuals interact through networks of acquaintances, we study the evolution of cooperation on model and real social networks through well known paradigmatic games. Using a new payoff scheme which leaves replicator dynamics invariant, we find that cooperation is sustainable in such networks, even in the difficult case of the prisoner’s dilemma. The evolution and stability of cooperation implies the condensation of game strategies into the existing community structures of the social network in which clusters of cooperators survive thanks to their higher connectivity towards other fellow cooperators. 相似文献
16.
M. Ángeles Serrano M. Boguñá A. Díaz-Guilera 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,50(1-2):249-254
We model the Internet as a network of interconnected Autonomous
Systems which self-organize under an absolute lack of centralized
control. Our aim is to capture how the Internet evolves by
reproducing the assembly that has led to its actual structure and,
to this end, we propose a growing weighted network model driven by
competition for resources and adaptation to maintain functionality
in a demand and supply balance. On the demand side, we consider the
environment, a pool of users which need to transfer information and
ask for service. On the supply side, ASs compete to gain users, but
to be able to provide service efficiently, they must adapt their
bandwidth as a function of their size. Hence, the Internet is not
modeled as an isolated system but the environment, in the form of a
pool of users, is also a fundamental part which must be taken into
account. ASs compete for users and big and small come up, so that
not all ASs are identical. New connections between ASs are made or
old ones are reinforced according to the adaptation needs. Thus, the
evolution of the Internet can not be fully understood if just
described as a technological isolated system. A socio-economic
perspective must also be considered. 相似文献
17.
R. F.S. Andrade J. G.V. Miranda S. T.R. Pinho T. P. Lobão 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,61(2):247-256
A concept of higher order neighborhood in complex networks,
introduced previously [Phys. Rev. E 73, 046101 (2006)], is systematically
explored to investigate larger scale structures in complex networks. The
basic idea is to consider each higher order neighborhood as a network in
itself, represented by a corresponding adjacency matrix, and to settle a
plenty of new parameters in order to obtain a best characterization of the
whole network. Usual network indices are then used to evaluate the
properties of each neighborhood. The identification of high order
neighborhoods is also regarded as intermediary step towards the evaluation
of global network properties, like the diameter, average shortest path
between node, and network fractal dimension. Results for a large number of
typical networks are presented and discussed. 相似文献
18.
In this paper, a new algorithm is proposed, which uses only local information to analyze community structures in complex networks. The algorithm is based on a table that describes a network and a virtual cache similar to the cache in the computer structure. When being tested on some typical computer-generated and real-world networks, this algorithm demonstrates excellent detection results and very fast processing performance, much faster than the existing comparable algorithms of the same kind. 相似文献
19.
This paper studies the evolutionary ultimatum game on networks when agents have incomplete information about the strategies of their neighborhood agents. Our model assumes that agents may initially display low fairness behavior, and therefore, may have to learn and develop their own strategies in this unknown environment. The Genetic Algorithm Learning Classifier System (GALCS) is used in the model as the agent strategy learning rule. Aside from the Watts-Strogatz (WS) small-world network and its variations, the present paper also extends the spatial ultimatum game to the Barabási-Albert (BA) scale-free network. Simulation results show that the fairness level achieved is lower than in situations where agents have complete information about other agents’ strategies. The research results display that fairness behavior will always emerge regardless of the distribution of the initial strategies. If the strategies are randomly distributed on the network, then the long-term agent fairness levels achieved are very close given unchanged learning parameters. Neighborhood size also has little effect on the fairness level attained. The simulation results also imply that WS small-world and BA scale-free networks have different effects on the spatial ultimatum game. In ultimatum game on networks with incomplete information, the WS small-world network and its variations favor the emergence of fairness behavior slightly more than the BA network where agents are heterogeneously structured. 相似文献
20.
Detecting communities in complex networks is of considerable importance for understanding both the structure and function of the networks. Here, we propose a class of improved algorithms for community detection, by combining the betweenness algorithm of Girvan and Newman with the edge weight defined by the edge-clustering coefficient. The improved algorithms are tested on some artificial and real-world networks, and the results show that they can detect communities of networks more effectively in both unweighted and weighted cases. In addition, the technique for improving the betweenness algorithm in this paper, thanks to its compatibility, can directly be applied to various detection algorithms. 相似文献