03.12.2012 Views

PERCOLATION AND DISORDERED SYSTEMS Geoffrey GRIMMETT

PERCOLATION AND DISORDERED SYSTEMS Geoffrey GRIMMETT

PERCOLATION AND DISORDERED SYSTEMS Geoffrey GRIMMETT

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

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.

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!