Exponential maps of a polynomial ring in two variables
Let k be a field. We show that the ring of invariants of every exponential map on k[x,y] is generated by the image of x or y under a composition of triangular automorphisms. From this we obtain two well-known theorems on k[x,y] with no restriction on the characteristic of k: the Rentschler–Miyanishi theorem and the Jung–van der Kulk theorem
Publisher: 'Springer Science and Business Media LLC'
DOI identifier: 10.1007/s40863-019-00124-9
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