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D.15.2.31 arrIsFree

Procedure from library arr.lib (see arr_lib).

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

Example:
 
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
See also: arrDer; arrExponents; arrIsFree.