Abstract
Due to Rentschler, Miyanishi and Kojima, the invariant ring for a $\mathrm{G}_a$-action on the affine plane over an arbitrary field is generated by one coordinate. In this note, we give a new short proof for this result using the automorphism theorem of Jung and van der Kulk.
Funding Statement
Partly supported by JSPS KAKENHI Grant Numbers 15K04826, 24340006.
Citation
Shigeru Kuroda. "The automorphism theorem and additive group actions on the affine plane." Nihonkai Math. J. 28 (1) 65 - 68, 2017.
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