  We present an inverse scattering transform approach to the Cauchy problem on
the line for the Degasperis--Procesi equation $u_t-u_{txx}+3\omega
u_x+4uu_x=3u_xu_{xx}+uu_{xxx}$ in the form of an associated Riemann-Hilbert
problem. This approach allows us to give a representation of the solution to
the Cauchy problem, which can be efficiently used in studying its long-time
behavior.
