> 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.


      Werner