PERCOLATION AND DISORDERED SYSTEMS Geoffrey GRIMMETT
PERCOLATION AND DISORDERED SYSTEMS Geoffrey GRIMMETT
PERCOLATION AND DISORDERED SYSTEMS Geoffrey GRIMMETT
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Percolation and Disordered Systems 273<br />
Fig. 13.1. A primal configuration ω (with solid lines) and its dual configuration ω d<br />
(with dashed lines). The arrows join the given vertices of the dual to a dual vertex<br />
in the infinite face. Note that each face of the primal graph (including the infinite<br />
face) contains a unique component of the dual graph.<br />
which is to say that<br />
(13.32) φG,p,q(ω) = φ G d ,p d ,q(ω d ) for ω ∈ ΩE,<br />
where the dual parameter p d is given according to<br />
(13.33)<br />
pd q(1 − p)<br />
= .<br />
1 − pd p<br />
The unique fixed point of the mapping p ↦→ pd is easily seen to be given by<br />
p = κq where<br />
√<br />
q<br />
κq =<br />
1 + √ q .<br />
If we keep track of the constants of proportionality in the above calculation,<br />
we find that the partition function<br />
ZG,p,q = �<br />
satisfies the duality relation<br />
ω∈ΩE<br />
|V |−1<br />
(13.34) ZG,p,q = q<br />
which, when p = p d = κq, becomes<br />
p |η(ω)| (1 − p) |E\η(ω)| q k(ω)<br />
� 1 − p<br />
p d<br />
� |E|<br />
Z G d ,p d ,q<br />
|V |−1−1<br />
(13.35) ZG,κq,q = q 2 |E| ZGd ,κq,q.<br />
We shall find a use for this later.