**
Below is the ascii version of the abstract for 99-280.
The html version should be ready soon.**Georgii H.O., Higuchi Y.
Percolation and number of phases in the 2D Ising
model
(62K, LaTeX)
ABSTRACT. We reconsider the percolation approach of Russo, Aizenman and Higuchi
for showing that there exist only two phases in the Ising model on the
square lattice.
We give a fairly short alternative proof which is only based on FKG
monotonicity and avoids the use of GKS-type inequalities
originally needed for some background results. Our proof extends to
the Ising model on other planar lattices such as the triangular
and honeycomb lattice.
We can also treat the Ising antiferromagnet in an external field and
the hard-core lattice gas model on $Z^2$.