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Proc Natl Acad Sci U S A. 2012 Mar 6;109(10):3682-7. doi: 10.1073/pnas.1200709109. Epub 2012 Feb 21.

Graph fission in an evolving voter model.

Author information

1
Department of Mathematics, Duke University, Box 90320, Durham, NC 27708, USA. rtd@math.duke.edu

Abstract

We consider a simplified model of a social network in which individuals have one of two opinions (called 0 and 1) and their opinions and the network connections coevolve. Edges are picked at random. If the two connected individuals hold different opinions then, with probability 1 - α, one imitates the opinion of the other; otherwise (i.e., with probability α), the link between them is broken and one of them makes a new connection to an individual chosen at random (i) from those with the same opinion or (ii) from the network as a whole. The evolution of the system stops when there are no longer any discordant edges connecting individuals with different opinions. Letting ρ be the fraction of voters holding the minority opinion after the evolution stops, we are interested in how ρ depends on α and the initial fraction u of voters with opinion 1. In case (i), there is a critical value α(c) which does not depend on u, with ρ ≈ u for α > α(c) and ρ ≈ 0 for α < α(c). In case (ii), the transition point α(c)(u) depends on the initial density u. For α > α(c)(u), ρ ≈ u, but for α < α(c)(u), we have ρ(α,u) = ρ(α,1/2). Using simulations and approximate calculations, we explain why these two nearly identical models have such dramatically different phase transitions.

PMID:
22355142
PMCID:
PMC3309720
DOI:
10.1073/pnas.1200709109
[Indexed for MEDLINE]
Free PMC Article

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