Symmetric Utumi quotient rings of Ore extensions by skew derivations

Abstract:

Let $R$ be a ring, $X$ a sequence of noncommuting indeterminates $x_1,x_2,\ldots$ and $D$ a sequence of skew derivations $\delta _1,\delta _2,\ldots$, where each $\delta _i$ is a $\sigma _i$-derivation of $R$. The Ore extension of $R$ by $D$, denoted by $R[X;D]$, is the ring generated by $R$ and $X$ subjected to the rule $x_ir=\sigma _i(r)x_i+\delta _i(r)$ for each $i$. If $|X|\ge 2$ and $R$ is a domain, we show that the symmetric maximal ring of quotients of $R[X;D]$ is equal to $U_s(R)[X;D]$, where $U_s(R)$ is the symmetric maximal ring of quotients of $R$.