96,381 research outputs found
Personalized Degrees: Effects on Link Formation in Dynamic Networks from an Egocentric Perspective
Understanding mechanisms driving link formation in dynamic social networks is
a long-standing problem that has implications to understanding social structure
as well as link prediction and recommendation. Social networks exhibit a high
degree of transitivity, which explains the successes of common neighbor-based
methods for link prediction. In this paper, we examine mechanisms behind link
formation from the perspective of an ego node. We introduce the notion of
personalized degree for each neighbor node of the ego, which is the number of
other neighbors a particular neighbor is connected to. From empirical analyses
on four on-line social network datasets, we find that neighbors with higher
personalized degree are more likely to lead to new link formations when they
serve as common neighbors with other nodes, both in undirected and directed
settings. This is complementary to the finding of Adamic and Adar that neighbor
nodes with higher (global) degree are less likely to lead to new link
formations. Furthermore, on directed networks, we find that personalized
out-degree has a stronger effect on link formation than personalized in-degree,
whereas global in-degree has a stronger effect than global out-degree. We
validate our empirical findings through several link recommendation experiments
and observe that incorporating both personalized and global degree into link
recommendation greatly improves accuracy.Comment: To appear at the 10th International Workshop on Modeling Social Media
co-located with the Web Conference 201
Link Prediction in Complex Networks: A Survey
Link prediction in complex networks has attracted increasing attention from
both physical and computer science communities. The algorithms can be used to
extract missing information, identify spurious interactions, evaluate network
evolving mechanisms, and so on. This article summaries recent progress about
link prediction algorithms, emphasizing on the contributions from physical
perspectives and approaches, such as the random-walk-based methods and the
maximum likelihood methods. We also introduce three typical applications:
reconstruction of networks, evaluation of network evolving mechanism and
classification of partially labelled networks. Finally, we introduce some
applications and outline future challenges of link prediction algorithms.Comment: 44 pages, 5 figure
Urban characteristics attributable to density-driven tie formation
Motivated by empirical evidence on the interplay between geography,
population density and societal interaction, we propose a generative process
for the evolution of social structure in cities. Our analytical and simulation
results predict both super-linear scaling of social tie density and information
flow as a function of the population. We demonstrate that our model provides a
robust and accurate fit for the dependency of city characteristics with city
size, ranging from individual-level dyadic interactions (number of
acquaintances, volume of communication) to population-level variables
(contagious disease rates, patenting activity, economic productivity and crime)
without the need to appeal to modularity, specialization, or hierarchy.Comment: Early version of this paper was presented in NetSci 2012 as a
contributed talk in June 2012. An improved version of this paper is published
in Nature Communications in June 2013. It has 14 pages and 5 figure
A nonuniform popularity-similarity optimization (nPSO) model to efficiently generate realistic complex networks with communities
The hidden metric space behind complex network topologies is a fervid topic
in current network science and the hyperbolic space is one of the most studied,
because it seems associated to the structural organization of many real complex
systems. The Popularity-Similarity-Optimization (PSO) model simulates how
random geometric graphs grow in the hyperbolic space, reproducing strong
clustering and scale-free degree distribution, however it misses to reproduce
an important feature of real complex networks, which is the community
organization. The Geometrical-Preferential-Attachment (GPA) model was recently
developed to confer to the PSO also a community structure, which is obtained by
forcing different angular regions of the hyperbolic disk to have variable level
of attractiveness. However, the number and size of the communities cannot be
explicitly controlled in the GPA, which is a clear limitation for real
applications. Here, we introduce the nonuniform PSO (nPSO) model that,
differently from GPA, forces heterogeneous angular node attractiveness by
sampling the angular coordinates from a tailored nonuniform probability
distribution, for instance a mixture of Gaussians. The nPSO differs from GPA in
other three aspects: it allows to explicitly fix the number and size of
communities; it allows to tune their mixing property through the network
temperature; it is efficient to generate networks with high clustering. After
several tests we propose the nPSO as a valid and efficient model to generate
networks with communities in the hyperbolic space, which can be adopted as a
realistic benchmark for different tasks such as community detection and link
prediction
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