The Riemann-Hilbert Problem for the Bi-Orthogonal Polynomials
  For the bi-orthogonal polynomials with the third degree polynomial potential functions, the 3 x 3 matrix Riemann-Hilbert problem is explicitly constructed. The developed approach admits an extension to the bi-orthogonal polynomials with arbitrary polynomial potentials. 
Andrei A. Kapaev (PDMI, St Petersburg)