Ring $R_{ 148 }$

Description:

Let $S = \mathbb Q[\ldots, x_{-1}, x_0, x_1, \ldots]$, $I = ( \{ x_k x_{k + a} x_{k + 2a}: k \in \Bbb Z, a \in \Bbb Z \setminus \{0\} \} )$ an ideal of $S$, and $\sigma$ the $\mathbb Q$-automorphism of $S$ such that $\sigma(x_i) = x_{i + 1}$ for all $i$. Then, $\sigma$ induces a $\mathbb Q$-automorphism of $T = S/I$. ($T$ is $R_{158}$) The required ring is the skew polynomial ring $R=T[x; \sigma]$.

Keywords twisted (skew) polynomial ring