  We consider the initial value problems of the Kadomtsev-Petviashvili (KP)
equation for symmetric V-shape initial waves consisting of two semi-infinite
line solitons with the same amplitude. Numerical simulations show that the
solutions of the initial value problem approach asymptotically to certain exact
solutions of the KP equation found recently in [Chakravarty and Kodama, JPA, 41
(2008) 275209]. We then use a chord diagram to explain the asymptotic result.
We also demonstrate a real experiment of shallow water wave which may represent
the solution discussed in this Letter.
