We analyze the long-time asymptotics for the Degasperis--Procesi equation on
the half-line. By applying nonlinear steepest descent techniques to an
associated 3×3-matrix valued Riemann--Hilbert problem, we find an
explicit formula for the leading order asymptotics of the solution in the
similarity region in terms of the initial and boundary values.Comment: 61 pages, 11 figure