James Smith wrote:
> is it possible to get a longer arrow, and one with a solid head, in the
> following?
>
> +++
>
> \usepackage{amsmath}
>
> \[
> R_i' \overset{S_{i+1}'}\longrightarrow R_{i+1}'
> \]
>
>
\[
R_i'\xrightarrow{S_{i+1}'} R_{i+1}'
\]
Herbert