Originally, harmonic morphisms were defined as continuous mappings φ:X → X' between harmonic spaces such that h'∘φ remains harmonic whenever h' is harmonic, see [1], p. 20. In general linear axiomatic potential theory, one has to replace harmonic functions h' by hyperharmonic functions u' in this definition, in order to obtain an interesting class of mappings, see [3], Remark 2.3. The modified definition appears to be equivalent with the original one, provided X' is a Bauer space, i.e., a harmonic space with a base consisting of regular sets, see [3], Theorem 2.4. To extend the linear proof of this result directly into the recent non-linear theories fails, even in the case of semi-classical non-linear considerations [6]. The aim of this note is to give a modified proof which settles such difficulties in the quasi-linear theories [4], [5].
@article{bwmeta1.element.bwnjournal-article-bcpv27z1p271bwm, author = {Laine, Ilpo}, title = {Harmonic morphisms and non-linear potential theory}, journal = {Banach Center Publications}, volume = {27}, year = {1992}, pages = {271-275}, zbl = {0793.31008}, language = {en}, url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-bcpv27z1p271bwm} }
Laine, Ilpo. Harmonic morphisms and non-linear potential theory. Banach Center Publications, Tome 27 (1992) pp. 271-275. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-bcpv27z1p271bwm/
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