142,302 research outputs found
Community Structure Characterization
This entry discusses the problem of describing some communities identified in
a complex network of interest, in a way allowing to interpret them. We suppose
the community structure has already been detected through one of the many
methods proposed in the literature. The question is then to know how to extract
valuable information from this first result, in order to allow human
interpretation. This requires subsequent processing, which we describe in the
rest of this entry
Characterizing time series : when Granger causality triggers complex networks
In this paper, we propose a new approach to characterize time series with noise perturbations in both the time and frequency domains by combining Granger causality and complex networks. We construct directed and weighted complex networks from time series and use representative network measures to describe their physical and topological properties. Through analyzing the typical dynamical behaviors of some physical models and the MIT-BIH* human electrocardiogram data sets, we show that the proposed approach is able to capture and characterize various dynamics and has much potential for analyzing real-world time series of rather short length
Multilayer Complex Network Descriptors for Color-Texture Characterization
A new method based on complex networks is proposed for color-texture
analysis. The proposal consists on modeling the image as a multilayer complex
network where each color channel is a layer, and each pixel (in each color
channel) is represented as a network vertex. The network dynamic evolution is
accessed using a set of modeling parameters (radii and thresholds), and new
characterization techniques are introduced to capt information regarding within
and between color channel spatial interaction. An automatic and adaptive
approach for threshold selection is also proposed. We conduct classification
experiments on 5 well-known datasets: Vistex, Usptex, Outex13, CURet and MBT.
Results among various literature methods are compared, including deep
convolutional neural networks with pre-trained architectures. The proposed
method presented the highest overall performance over the 5 datasets, with 97.7
of mean accuracy against 97.0 achieved by the ResNet convolutional neural
network with 50 layers.Comment: 20 pages, 7 figures and 4 table
Hierarchical Features of Large-Scale Cortical Connectivity
The analysis of complex networks has revealed patterns of organization in a
variety of natural and artificial systems, including neuronal networks of the
brain at multiple scales. In this paper, we describe a novel analysis of the
large-scale connectivity between regions of the mammalian cerebral cortex,
utilizing a set of hierarchical measurements proposed recently. We examine
previously identified functional clusters of brain regions in macaque visual
cortex and cat cortex and find significant differences between such clusters in
terms of several hierarchical measures, revealing differences in how these
clusters are embedded in the overall cortical architecture. For example, the
ventral cluster of visual cortex maintains structurally more segregated, less
divergent connections than the dorsal cluster, which may point to functionally
different roles of their constituent brain regions.Comment: 17 pages, 6 figure
What are the Best Hierarchical Descriptors for Complex Networks?
This work reviews several hierarchical measurements of the topology of
complex networks and then applies feature selection concepts and methods in
order to quantify the relative importance of each measurement with respect to
the discrimination between four representative theoretical network models,
namely Erd\"{o}s-R\'enyi, Barab\'asi-Albert, Watts-Strogatz as well as a
geographical type of network. The obtained results confirmed that the four
models can be well-separated by using a combination of measurements. In
addition, the relative contribution of each considered feature for the overall
discrimination of the models was quantified in terms of the respective weights
in the canonical projection into two dimensions, with the traditional
clustering coefficient, hierarchical clustering coefficient and neighborhood
clustering coefficient resulting particularly effective. Interestingly, the
average shortest path length and hierarchical node degrees contributed little
for the separation of the four network models.Comment: 9 pages, 4 figure
A Method for Characterizing Communities in Dynamic Attributed Complex Networks
Many methods have been proposed to detect communities, not only in plain, but
also in attributed, directed or even dynamic complex networks. In its simplest
form, a community structure takes the form of a partition of the node set. From
the modeling point of view, to be of some utility, this partition must then be
characterized relatively to the properties of the studied system. However, if
most of the existing works focus on defining methods for the detection of
communities, only very few try to tackle this interpretation problem. Moreover,
the existing approaches are limited either in the type of data they handle, or
by the nature of the results they output. In this work, we propose a method to
efficiently support such a characterization task. We first define a
sequence-based representation of networks, combining temporal information,
topological measures, and nodal attributes. We then describe how to identify
the most emerging sequential patterns of this dataset, and use them to
characterize the communities. We also show how to detect unusual behavior in a
community, and highlight outliers. Finally, as an illustration, we apply our
method to a network of scientific collaborations.Comment: IEEE/ACM International Conference on Advances in Social Network
Analysis and Mining (ASONAM), P\'ekin : China (2014
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