string := *top*.

*list* := *top*.

*ne-list* := *list* &
 [ FIRST *top*,
   REST *list* ].

*null* := *list*.

synsem-struc := *top* &
[ CATEGORY cat,
  NUMAGR agr ].

cat := *top*.

s := cat.

np := cat.

vp := cat.

det := cat.

n := cat.

agr := *top*.

sg := agr.

pl := agr.

phrase := synsem-struc &
[ ARGS *list* ].

lexeme := synsem-struc &
[ ORTH string ].

sg-lexeme := lexeme &
[ NUMAGR sg ].

pl-lexeme := lexeme &
[ NUMAGR pl ].

root := phrase &
[ CATEGORY s ].