** 1978
**

*G. Gallavotti, F. Guerra, S. Miracle-Sol\'e*

**A comment to the talk by E. Seiler**

*In {\it Mathematical problems in
theoretical Physics}, ed. G. Dell'Antonio, S.Doplicher,
G. Jona--Lasinio, Lecture notes in Physics, {\bf 80}, 436--438, 1978*

**Abstract**

A comment providing a proof that the $Z^2$ gauge theory had a phase transition
area-perimeter for the Wilson's loop expectation