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Negative Correlation in Graphs and Matroids

Published online by Cambridge University Press:  01 May 2008

CHARLES SEMPLE  and
DOMINIC WELSH
CHARLES SEMPLE
Affiliation:
Department of Mathematics and Statistics, University of Canterbury, Christchurch, New Zealand (e-mail: c.semple@math.canterbury.ac.nz)
DOMINIC WELSH
Affiliation:
Merton College, University of Oxford, Oxford, UK (e-mail: d.welsh@maths.ox.ac.uk)
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Abstract

The following two conjectures arose in the work of Grimmett and Winkler, and Pemantle: the uniformly random forest F and the uniformly random connected subgraph C of a finite graph G have the edge-negative association property. In other words, for all distinct edges e and f of G, the probability that F (respectively, C) contains e conditioned on containing f is less than or equal to the probability that F (respectively, C) contains e. Grimmett and Winkler showed that the first conjecture is true for all simple graphs on 8 vertices and all graphs on 9 vertices with at most 18 edges. In this paper, we describe an infinite, nontrivial class of graphs and matroids for which a generalized version of both conjectures holds.

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Type
Paper
Information
Combinatorics, Probability and Computing , Volume 17 , Issue 3 , May 2008 , pp. 423 - 435
Copyright
Copyright © Cambridge University Press 2008

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