> How can we use AMSMATH symbols in groff? Is it possible or eqn needs
> more code?
(1) Amsmath fonts are by default only available for -Tdvi. However,
it is rather straightforward to add Type 1 versions of the fonts
to the PS backend. The only tedious work is to harmonize the
glyph names between the dvi and ps backends. For example, glyph
`squaredot' (in TeXLive's msam10.pfb) is called `boxdot' in the
dvi backend. If this is of no importance, a simple run of
afmtodit should give you a usable groff font metric file for -Tps.
(2) Within eqn data, you can use e.g. \[boxdot]. If necessary, look
into `eqnrc' how to use sdefine to change a symbol's category.