D.15.1.31 arrIsFree

Usage:

arrIsFree(A); arr A, multarr A

Return:

[0,1] 1 if the (multi-)arrangement is free, i.e. Der(A) is a free module

Note:

only defined for central arrangements

LIB "arr.lib";
ring R = 0,(x,y,z),dp;
arr A3 = arrBoolean(3);
arr B3 = arrTypeB(3);
arr G = ideal(x,y,z,x+y+z);
arrIsFree(A3);
==> 1
arrIsFree(B3);
==> 1
arrIsFree(G);
==> 0