DBAR problem

The DBAR problem, or the ${\displaystyle {\bar {\partial }}}$-problem, is the problem of solving the differential equation $${\displaystyle {\bar {\partial }}f(z,{\bar {z}})=g(z)}$$for the function ${\displaystyle f(z,{\bar {z}})}$, where ${\displaystyle g(z)}$is assumed to be known and ${\displaystyle z=x+iy}$is a complex number in a domain ${\displaystyle R\subseteq \mathbb {C} }$. The operator ${\displaystyle {\bar {\partial }}}$is called the DBAR operator: $${\displaystyle {\bar {\partial }}={\frac {1}{2}}\left({\frac {\partial }{\partial x}}+i{\frac {\partial }{\partial y}}\right)}$$

The DBAR operator is nothing other than the complex conjugate of the operator $${\displaystyle \partial ={\frac {\partial }{\partial z}}={\frac {1}{2}}\left({\frac {\partial }{\partial x}}-i{\frac {\partial }{\partial y}}\right)}$$denoting the usual differentiation in the complex ${\displaystyle z}$-plane.

The DBAR problem is of key importance in the theory of integrable systems, Schrödinger operators and generalizes the Riemann–Hilbert problem.

• 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.