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 277<br />
Fig. 13.3. The interior edges I of Γ are marked in the leftmost picture, and the dual<br />
Id in the centre picture (the vertices marked with a cross are identified as a single<br />
vertex). The shifted set I∗ = Id + ( 1 1<br />
, ) is drawn in the rightmost picture. Note<br />
2 2<br />
that I∗ ⊆ I ∪ Γ ′ .<br />
Now assume that p = √ q/(1 + √ q), so that p = p d . Then, by (13.41)–<br />
(13.43) and (13.35),<br />
(13.44)<br />
φ 1 � � |Γ|<br />
B,p,q OC(Γ) = (1 − p) Z1 E (Γ)ZI<br />
Z1 B,p,q<br />
= (1 − p) |Γ| q m−1−1 2 |I|Z1 E (Γ)Z1 Id ,p,q<br />
Z1 B,p,q<br />
≤ (1 − p) |Γ| q m−1−1<br />
2 |I| .<br />
Since each vertex of B (inside Γ) has degree 4, we have that<br />
whence<br />
4m = 2|I| + |Γ|,<br />
(13.45) φ 1 � � 1 |Γ|<br />
B,p,q OC(Γ) ≤ (1 − p) q 4 |Γ|−1 = 1<br />
q<br />
�<br />
q<br />
(1 + √ q) 4<br />
� |Γ|/4<br />
.<br />
The number of dual circuits of B having length l and containing the origin<br />
in their interior is no greater than lal, where al is the number of self-avoiding<br />
walks of L 2 beginning at the origin and having length l. Therefore<br />
�<br />
Γ<br />
φ 1 � �<br />
B,p,q OC(Γ) ≤<br />
∞�<br />
l=4<br />
1<br />
q<br />
�<br />
q<br />
(1 + √ q) 4<br />
�l/4 lal.<br />
Now l −1 log al → µ as l → ∞, where µ is the connective constant of L 2 .<br />
Suppose now that q > Q, so that qµ 4 < (1 + √ q) 4 . It follows that there<br />
exists A(q) (< ∞) such that<br />
�<br />
Γ<br />
φ 1 � �<br />
B,p,q OC(Γ) < A(q) for all n.