Intersection |
Syntax |
Intersection(E_1:LIST,....,E_n:LIST):LIST Intersection(E_1:IDEAL,...,E_n:IDEAL):IDEAL Intersection(E_1:MODULE,....,E_n:MODULE):MODULE |
Description |
Intersection
returns the intersection of E_1,...,E_n
.
In the case where the E_i
's are lists, it returns the elements common
to all of the lists.
HIntersection
. To compute the
intersection of ideals corresponding to zero-dimensional schemes, see
the commands GBM and HGBM.
Example |
Use R ::= Q[x,y,z]; Points := [[0,0],[1,0],[0,1],[1,1]]; -- a list of points in the plane I := Ideal(x,y); -- the ideal for the first point Foreach P In Points Do I := Intersection(I,Ideal(x-P[1]z,y-P[2]z)); EndForeach; I; -- the ideal for (the projective closure of) Points Ideal(y^2 - yz, x^2 - xz) ------------------------------- Intersection(["a","b","c"],["b","c","d"]); ["b", "c"] ------------------------------- It = Intersection(Ideal(x,y),Ideal(y^2,z)); TRUE ------------------------------- |
See Also |