>
> I think 1(b) above meets this need. If you want a still longer arrow
> you can try "\longrightarrow" instead of "\rightarrow" in 1(a) or 2
>
or \xrightarrow{\enspace\cong\enspace}
since \xrightarrow adjust its own length.
/daleif
``You cannot help men permanently by doing for them
what they could and should do for themselves. ''
-- Abraham Lincoln