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Initial‐Boundary Value Problem for Integrable Nonlinear Evolution Equation with 3 × 3 Lax Pairs on the Interval
Author(s) -
Xu Jian,
Fan Engui
Publication year - 2016
Publication title -
studies in applied mathematics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.164
H-Index - 46
eISSN - 1467-9590
pISSN - 0022-2526
DOI - 10.1111/sapm.12108
Subject(s) - mathematics , boundary value problem , mathematical analysis , integrable system , nonlinear system , mixed boundary condition , lax pair , interval (graph theory) , initial value problem , robin boundary condition , free boundary problem , boundary (topology) , partial differential equation , physics , combinatorics , quantum mechanics
We present an approach for analyzing initial‐boundary value problems which are formulated on the finite interval ( 0 ≤ x ≤ L , where L is a positive constant) for integrable equation whose Lax pairs involve 3 × 3 matrices. Boundary value problems for integrable nonlinear evolution partial differential equations (PDEs) can be analyzed by the unified method introduced by Fokas and developed by him and his collaborators. In this paper, we show that the solution can be expressed in terms of the solution of a 3 × 3 Riemann–Hilbert problem (RHP). The relevant jump matrices are explicitly given in terms of the three matrix‐value spectral functions s ( k ) , S ( k ) , andS L ( k ) , which in turn are defined in terms of the initial values, boundary values at x = 0 , and boundary values at x = L , respectively. However, these spectral functions are not independent; they satisfy a global relation. Here, we show that the characterization of the unknown boundary values in terms of the given initial and boundary data is explicitly described for a nonlinear evolution PDE defined on the interval. Also, we show that in the limit when the length of the interval tends to infinity, the relevant formulas reduce to the analogous formulas obtained for the case of boundary value problems formulated on the half‐line.