Get the double dual (S2 - identification) of an ideal. If KnownNormal is false (default is true), then the computer will first check whether the ambient ring is normal, if it is not then it will perform a (possibly) slower check that will definitely give the right answer.
i1 : R = QQ[x,y,z]/ideal(x^2-y*z)
o1 = R
o1 : QuotientRing
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i2 : m = ideal(x,y,z)
o2 = ideal (x, y, z)
o2 : Ideal of R
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i3 : dualizeIdeal(m)
o3 = ideal x
o3 : Ideal of R
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i4 : I = ideal(x,y)
o4 = ideal (x, y)
o4 : Ideal of R
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i5 : dualizeIdeal(I)
o5 = ideal (z, x)
o5 : Ideal of R
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i6 : dualizeIdeal(I^2)
o6 = ideal z
o6 : Ideal of R
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i7 : dualizeIdeal(I^3)
2
o7 = ideal (z , x*z)
o7 : Ideal of R
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