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3.7 intersect

Syntax:
intersect (expression_list of ideal_expression )
intersect (expression_list of module_expression )

Type:
ideal, resp. module

Purpose:
computes the intersection of ideals, resp. modules.

Example:

 
// from [BGV], p.213, Ex.2.5
ring r2=0,(x,y),dp;
ncalgebra(-1,0);
module M=[x,x],[y,0];
module N=[0,y^2],[y,x];
option(redSB);
module Res;
Res=intersect(M,N);
print(Res);
==> y2, 0, 
==> -xy,xy2
kill r2;

// from [BGV], p.148, Ex.3.8
LIB "ncalg.lib";
ring r=0,(x,d),dp;
Weyl(); // supply r with the structure of the 1st Weyl algebra
ideal I = x+d^2;
ideal J = d-1;
ideal H = intersect(I,J);
H;
==> H[1]=d4+xd2-2d3-2xd+d2+x+2d-2
==> H[2]=xd3+x2d-xd2+d3-x2+xd-2d2-x+1


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