Abstrakt
Countour methods first emerged in the probabilistic proof of long range order for lattice models. With help of cluster expansions, they turned into a powerful tool for investigation of phase transitions for a large call of models that allows to study various phenomena involving coexisting phases (interfaces, equilibrium crystal shapes) as well as the behaviour in finite volume including the asymptotics of the phase transition points as well as the determination of asymptotic location of zeros of partition functions