Harmonic morphisms in nonlinear potential theory

J. Heinonen, T. Kilpeläinen, O. Martio
1992 Nagoya mathematical journal  
This article concerns the following problem: given a family of partial differential operators with similar structure and given a continuous mappingffrom an open setΩinRnintoRn, then when doesfpull back the solutions of one equation in the family to solutions of another equation in that family? This problem is typical in the theory of differential equations when one wants to use a coordinate change to study solutions in a different environment.
doi:10.1017/s0027763000003937 fatcat:zs53ktg5m5b5nhldq7peiq6uc4