gb

a gb b
array a; array b;
b : [g ii];  array g; array in; g is a Grobner basis of f
             in the ring of differential operators.
            ii is the initial ideal in case of w is given or <<a>> belongs
            to a ring. In the other cases, it returns the initial monominal.
a : [f ];    array f;  f is a set of generators of an ideal in a ring.
a : [f v];   array f; string v;  v is the variables. 
a : [f v w]; array f; string v; array of array w; w is the weight matirx.
  
Example 1: [ [( (x Dx)^2 + (y Dy)^2 -1) ( x y Dx Dy -1)] (x,y) 
             [ [ (Dx) 1 ] ] ] gb pmat ; 
Example 2: 
To put h=1, type in, e.g., 
 [ [(2 x Dx + 3 y Dy+6) (2 y Dx + 3 x^2 Dy)] (x,y) 
   [[(x) -1 (Dx) 1 (y) -1 (Dy) 1]]] gb /gg set gg dehomogenize pmat ;
  
Example 3: [ [( (x Dx)^2 + (y Dy)^2 -1) (  x y Dx Dy -1)] (x,y) 
             [ [ (Dx) 1 (Dy) 1] ] ] gb pmat ; 
  
Example 4: [[ [(x^2) (y+x)] [(x+y) (y^3)] [(2 x^2+x y) (y+x+x y^3)]] (x,y) 
             [ [ (x) -1 (y) -1] ] ] gb pmat ; 
  
cf. gb, groebner, groebner_sugar, syz.