  In this paper, we review a way to change nature of phase transition with
annealing methods in mind. Annealing methods are regarded as a general
technique to solve optimization problems efficiently. In annealing methods, we
introduce a controllable parameter which represents a kind of fluctuation and
decrease the parameter gradually. Annealing methods face with a difficulty when
a phase transition point exists during the protocol. Then, it is important to
develop a method to avoid the phase transition by introducing a new type of
fluctuation. By taking the Potts model for instance, we review a way to change
the phase transition nature. Although the method described in this paper does
not succeed to avoid the phase transition, we believe that the concept of the
method will be useful for optimization problems.
