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primaryDecompositionPseudomonomial -- primary decomposition of a square free pseudomonomial ideal

Synopsis

Description

The algorithm is implemented bitwise (using Macaulay2 bitwise operations), which makes calculations faster. Examples:
i1 : R=ZZ/2[x1,x2,x3,x4,x5];
i2 : I = ideal(x1*x2,x3*x4,x5);

o2 : Ideal of R
i3 : primaryDecompositionPseudomonomial(I) 

o3 = {ideal (x5, x1, x3), ideal (x5, x1, x4), ideal (x5, x2, x3), ideal (x5,
     ------------------------------------------------------------------------
     x2, x4)}

o3 : List
i4 : R=QQ[x1,x2,x3,x4,x5];
i5 : I = ideal(x1*(x2-1),(x3-1)*x4,x5);

o5 : Ideal of R
i6 : primaryDecompositionPseudomonomial(I) 

o6 = {ideal (x5, x1, x3 - 1), ideal (x5, x1, x4), ideal (x5, x2 - 1, x3 - 1),
     ------------------------------------------------------------------------
     ideal (x5, x2 - 1, x4)}

o6 : List
i7 : R=ZZ/2[x1,x2];
i8 : I = ideal(x1*(x2-1),(x1-1)*(x2-1),x1*x2,(x1-1)*x2);

o8 : Ideal of R
i9 : primaryDecompositionPseudomonomial(I) 

o9 = {}

o9 : List
i10 : R=QQ[x1,x2,x3,x4,x5];
i11 : I = ideal(x5,x1*(x3-1)*(x5-1));

o11 : Ideal of R
i12 : primaryDecompositionPseudomonomial(I) 

o12 = {ideal (x5, x1), ideal (x5, x3 - 1)}

o12 : List
i13 : R=ZZ/3[x1,x2];
i14 : I = ideal(x5,(x3-1));

o14 : Ideal of QQ[x1, x2, x3, x4, x5]
i15 : primaryDecompositionPseudomonomial(I) 

o15 = {ideal (x5, x3 - 1)}

o15 : List

Caveat

The algorithm finds a decomposition even if the base field is not QQ or ZZ/p

See also

Ways to use primaryDecompositionPseudomonomial :

For the programmer

The object primaryDecompositionPseudomonomial is a method function.