Ideal intersections in the ring of differential operators. [ I1 I2 V-list ] intersection : I1 and I2 are ideals, and V-list is a list of variables. It returns the ideal intersection of I1 and I2. Intersection is computed in the ring of differential operators. Example 1: [[[(x1) (x2)] [(x2) (x4)] (x1,x2,x3,x4)] intersection [(x2) (x4^2)] (x1,x2,x3,x4)] intersection :: Example 2: [[[(x1) (x2)] [(x2) (x4)] (x1,x2,x3,x4)] intersection [(x2) (x4^2)] (x1,x2,x3,x4)] intersection /ff set ff message [ ff [(x2^2) (x3) (x4)] (x1,x2,x3,x4)] intersection :: Example 3: [[[(x1) (x2)] [(x2) (x4^2)] (x1,x2,x3,x4)] intersection [(x2^2) (x3) (x4)] (x1,x2,x3,x4)] intersection ::

Nobuki Takayama 平成17年2月10日