161,827 research outputs found
Relay-Linking Models for Prominence and Obsolescence in Evolving Networks
The rate at which nodes in evolving social networks acquire links (friends,
citations) shows complex temporal dynamics. Preferential attachment and link
copying models, while enabling elegant analysis, only capture rich-gets-richer
effects, not aging and decline. Recent aging models are complex and heavily
parameterized; most involve estimating 1-3 parameters per node. These
parameters are intrinsic: they explain decline in terms of events in the past
of the same node, and do not explain, using the network, where the linking
attention might go instead. We argue that traditional characterization of
linking dynamics are insufficient to judge the faithfulness of models. We
propose a new temporal sketch of an evolving graph, and introduce several new
characterizations of a network's temporal dynamics. Then we propose a new
family of frugal aging models with no per-node parameters and only two global
parameters. Our model is based on a surprising inversion or undoing of triangle
completion, where an old node relays a citation to a younger follower in its
immediate vicinity. Despite very few parameters, the new family of models shows
remarkably better fit with real data. Before concluding, we analyze temporal
signatures for various research communities yielding further insights into
their comparative dynamics. To facilitate reproducible research, we shall soon
make all the codes and the processed dataset available in the public domain
Understanding Complex Systems: From Networks to Optimal Higher-Order Models
To better understand the structure and function of complex systems,
researchers often represent direct interactions between components in complex
systems with networks, assuming that indirect influence between distant
components can be modelled by paths. Such network models assume that actual
paths are memoryless. That is, the way a path continues as it passes through a
node does not depend on where it came from. Recent studies of data on actual
paths in complex systems question this assumption and instead indicate that
memory in paths does have considerable impact on central methods in network
science. A growing research community working with so-called higher-order
network models addresses this issue, seeking to take advantage of information
that conventional network representations disregard. Here we summarise the
progress in this area and outline remaining challenges calling for more
research.Comment: 8 pages, 4 figure
Three-feature model to reproduce the topology of citation networks and the effects from authors' visibility on their h-index
Various factors are believed to govern the selection of references in
citation networks, but a precise, quantitative determination of their
importance has remained elusive. In this paper, we show that three factors can
account for the referencing pattern of citation networks for two topics, namely
"graphenes" and "complex networks", thus allowing one to reproduce the
topological features of the networks built with papers being the nodes and the
edges established by citations. The most relevant factor was content
similarity, while the other two - in-degree (i.e. citation counts) and {age of
publication} had varying importance depending on the topic studied. This
dependence indicates that additional factors could play a role. Indeed, by
intuition one should expect the reputation (or visibility) of authors and/or
institutions to affect the referencing pattern, and this is only indirectly
considered via the in-degree that should correlate with such reputation.
Because information on reputation is not readily available, we simulated its
effect on artificial citation networks considering two communities with
distinct fitness (visibility) parameters. One community was assumed to have
twice the fitness value of the other, which amounts to a double probability for
a paper being cited. While the h-index for authors in the community with larger
fitness evolved with time with slightly higher values than for the control
network (no fitness considered), a drastic effect was noted for the community
with smaller fitness
Network-based ranking in social systems: three challenges
Ranking algorithms are pervasive in our increasingly digitized societies,
with important real-world applications including recommender systems, search
engines, and influencer marketing practices. From a network science
perspective, network-based ranking algorithms solve fundamental problems
related to the identification of vital nodes for the stability and dynamics of
a complex system. Despite the ubiquitous and successful applications of these
algorithms, we argue that our understanding of their performance and their
applications to real-world problems face three fundamental challenges: (i)
Rankings might be biased by various factors; (2) their effectiveness might be
limited to specific problems; and (3) agents' decisions driven by rankings
might result in potentially vicious feedback mechanisms and unhealthy systemic
consequences. Methods rooted in network science and agent-based modeling can
help us to understand and overcome these challenges.Comment: Perspective article. 9 pages, 3 figure
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