The Stacks project

Example 15.90.9. Let $k$ be a field and put

Then $(R, f)$ is not a glueing pair because the map $R[f^\infty ] \to R^\wedge [f^\infty ]$ is not injective as the image of $T_1$ is $f$-divisible in $R^\wedge$. For

the map $R[f^\infty ] \to R^\wedge [f^\infty ]$ is not surjective as the element $T_1 + fT_2 + f^2 T_3 + \ldots$ is not in the image. In particular, by Remark 15.90.8, these are both examples where $R \to R^\wedge$ is not flat.