2,611 research outputs found
On local weak limit and subgraph counts for sparse random graphs
We use an inequality of Sidorenko to show a general relation between local
and global subgraph counts and degree moments for locally weakly convergent
sequences of sparse random graphs. This yields an optimal criterion to check
when the asymptotic behaviour of graph statistics such as the clustering
coefficient and assortativity is determined by the local weak limit. As an
application we obtain new facts for several common models of sparse random
intersection graphs where the local weak limit, as we see here, is a simple
random clique tree corresponding to a certain two-type Galton-Watson branching
process
Moment-based parameter estimation in binomial random intersection graph models
Binomial random intersection graphs can be used as parsimonious statistical
models of large and sparse networks, with one parameter for the average degree
and another for transitivity, the tendency of neighbours of a node to be
connected. This paper discusses the estimation of these parameters from a
single observed instance of the graph, using moment estimators based on
observed degrees and frequencies of 2-stars and triangles. The observed data
set is assumed to be a subgraph induced by a set of nodes sampled from
the full set of nodes. We prove the consistency of the proposed estimators
by showing that the relative estimation error is small with high probability
for . As a byproduct, our analysis confirms that the
empirical transitivity coefficient of the graph is with high probability close
to the theoretical clustering coefficient of the model.Comment: 15 pages, 6 figure
A statistical network analysis of the HIV/AIDS epidemics in Cuba
The Cuban contact-tracing detection system set up in 1986 allowed the
reconstruction and analysis of the sexual network underlying the epidemic
(5,389 vertices and 4,073 edges, giant component of 2,386 nodes and 3,168
edges), shedding light onto the spread of HIV and the role of contact-tracing.
Clustering based on modularity optimization provides a better visualization and
understanding of the network, in combination with the study of covariates. The
graph has a globally low but heterogeneous density, with clusters of high
intraconnectivity but low interconnectivity. Though descriptive, our results
pave the way for incorporating structure when studying stochastic SIR epidemics
spreading on social networks
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