KnownDomain is an option for IdealStrategy. If it is false (default is true), then the computer will first check whether the ring is a domain, if it is not then it will revert to ModuleStrategy. If KnownDomain is set to true for a non-domain, then the function can return an incorrect answer.
i1 : R = QQ[x,y]/ideal(x*y); |
i2 : J = ideal(x,y); o2 : Ideal of R |
i3 : dualize(J, KnownDomain=>true) o3 = ideal x o3 : Ideal of R |
i4 : dualize(J, KnownDomain=>false) o4 = ideal (y, x) o4 : Ideal of R |