2 problems

Let $R$ be a commutative ring, let $R[\boldsymbol{x}]=R[x_1,\ldots,x_n]$, and let $\sigma\in\mathop{\rm Aut}\nolimits_R R[\boldsymbol{x}]$. For $r\geq 0$, write…

Let $k$ be a field and let $F\in \operatorname*{GA}_n(k)$ be a polynomial automorphism of affine $n$-space. The automorphism $F$ is stably tame if, after adjoining finitely many ne…