This function returns the primary decomposition of the ideal I.
Currently it responds ONLY for squarefree monomial ideals
(using the Alexander dual technique).
See PrimaryDecomposition0 for 0-dimensional ideals
and FrbPrimaryDecomposition for monomial ideals.
Example
/**/ use P ::= QQ[x,y,z];
/**/ PrimaryDecomposition(ideal(x*y, y*z, z*x));
[ideal(y, z), ideal(x, z), ideal(x, y)]