144 research outputs found
From the User to the Medium: Neural Profiling Across Web Communities
Online communities provide a unique way for individuals to access information
from those in similar circumstances, which can be critical for health
conditions that require daily and personalized management. As these groups and
topics often arise organically, identifying the types of topics discussed is
necessary to understand their needs. As well, these communities and people in
them can be quite diverse, and existing community detection methods have not
been extended towards evaluating these heterogeneities. This has been limited
as community detection methodologies have not focused on community detection
based on semantic relations between textual features of the user-generated
content. Thus here we develop an approach, NeuroCom, that optimally finds dense
groups of users as communities in a latent space inferred by neural
representation of published contents of users. By embedding of words and
messages, we show that NeuroCom demonstrates improved clustering and identifies
more nuanced discussion topics in contrast to other common unsupervised
learning approaches
A new hierarchical clustering algorithm to identify non-overlapping like-minded communities
A network has a non-overlapping community structure if the nodes of the
network can be partitioned into disjoint sets such that each node in a set is
densely connected to other nodes inside the set and sparsely connected to the
nodes out- side it. There are many metrics to validate the efficacy of such a
structure, such as clustering coefficient, betweenness, centrality, modularity
and like-mindedness. Many methods have been proposed to optimize some of these
metrics, but none of these works well on the recently introduced metric
like-mindedness. To solve this problem, we propose a be- havioral property
based algorithm to identify communities that optimize the like-mindedness
metric and compare its performance on this metric with other behavioral data
based methodologies as well as community detection methods that rely only on
structural data. We execute these algorithms on real-life datasets of
Filmtipset and Twitter and show that our algorithm performs better than the
existing algorithms with respect to the like-mindedness metric
Sequential Changepoint Approach for Online Community Detection
We present new algorithms for detecting the emergence of a community in large
networks from sequential observations. The networks are modeled using
Erdos-Renyi random graphs with edges forming between nodes in the community
with higher probability. Based on statistical changepoint detection
methodology, we develop three algorithms: the Exhaustive Search (ES), the
mixture, and the Hierarchical Mixture (H-Mix) methods. Performance of these
methods is evaluated by the average run length (ARL), which captures the
frequency of false alarms, and the detection delay. Numerical comparisons show
that the ES method performs the best; however, it is exponentially complex. The
mixture method is polynomially complex by exploiting the fact that the size of
the community is typically small in a large network. However, it may react to a
group of active edges that do not form a community. This issue is resolved by
the H-Mix method, which is based on a dendrogram decomposition of the network.
We present an asymptotic analytical expression for ARL of the mixture method
when the threshold is large. Numerical simulation verifies that our
approximation is accurate even in the non-asymptotic regime. Hence, it can be
used to determine a desired threshold efficiently. Finally, numerical examples
show that the mixture and the H-Mix methods can both detect a community quickly
with a lower complexity than the ES method.Comment: Submitted to 2014 INFORMS Workshop on Data Mining and Analytics and
an IEEE journa
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