Singular

D.14.1.19 arrRestrict

Return:

arr: the restricted hyperplane Arrangement (A^X)

Note:

A has to be non-empty.

Remarks:

We restrict A to the flat X, defined by the equations in A[v]. The restriction will only be performed, if the ideal defining the flat X is monomial (i.e. X is an intersection of coordinate planes). If the optional argument CC is given, the arrangement is transformed in such a way that X has the above form.

LIB "arr.lib";
ring S = 0,(x,y,z),dp;
arr A  = arrTypeB(3);
A;
==> _[1]=x-y
==> _[2]=x+y
==> _[3]=x-z
==> _[4]=x+z
==> _[5]=x
==> _[6]=y-z
==> _[7]=y+z
==> _[8]=y
==> _[9]=z
==> 
arrRestrict(A,9);
==> _[1]=x-y
==> _[2]=x+y
==> _[3]=x
==> _[4]=y
==> 
arrRestrict(A,4,"CC");
==> _[1]=1/2y-z
==> _[2]=1/2y+z
==> _[3]=y
==> _[4]=z
==> 
intvec v=5,8;
arrRestrict(A,v);
==> _[1]=-z
==>