;;; Types

syn-struc := *top* &
[ CATEG cat,
  NUMAGR agr ].

cat := *top*.

s := cat.

np := cat.

vp := cat.

det := cat.

n := cat.

agr := *top*.

sg := agr.

pl := agr.

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

;;; answer to exercise 3.5.10 - 1 
;;; AV - added 

agr-phrase := phrase & 
[ NUMAGR #1,
  ARGS [ FIRST [ NUMAGR #1 ],
         REST [ FIRST [ NUMAGR #1 ],
                REST *null* ]]] .

word := syn-struc &
[ ORTH string ].

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

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

;;; standard types

string := *top*.

*list* := *top*.

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

*null* := *list*.