Abstract
A review is made on recent developments of exact methods for solving soliton equations. Among various exact methods known nowadays, we mainly survey the bilinear transformation method (BTM) initiated by R. Hirota. The essence of the BTM is illustrated concretely by applying it to the KdV equation which is a typical soliton equation.
The relations of the BTM to other exact methods such as the inverse scattering method, the Backlund transformation and the Sato theory (the theory of τ function) are also discussed. Finally, some linearizable nonlinear equations are considered on the basis of the BTM.
