The DBAR problem, or the -problem, is the problem of solving the differential equation for the function , where is assumed to be known and is a complex number in a domain . The operator is called the DBAR operator:^[1]

The DBAR operator is nothing other than the complex conjugate of the operator denoting the usual differentiation in the complex -plane.

The DBAR problem is of key importance in the theory of integrable systems, Schrödinger operators and generalizes the Riemann–Hilbert problem.^[1][2][3]

• Ablowitz, Mark J.; Fokas, A. S. (2003). Complex Variables: Introduction and Applications. Cambridge University Press. pp. 516, 598–626. ISBN 978-0-521-53429-1.

• Haslinger, Friedrich (2014). The d-bar Neumann Problem and Schrödinger Operators. Walter de Gruyter GmbH & Co KG. ISBN 978-3-11-031535-6.[1]

• Konopelchenko, B. G. (2000). "On dbar-problem and integrable equations". arXiv:nlin/0002049.