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NoetherianOperators :: noetherianOperators

noetherianOperators -- Noetherian operators

Description

Let $R$ be a polynomial ring $R = K[x_1,\ldots,x_n]$ over a field $K$ of characteristic zero. Consider the Weyl algebra $D = R<dx_1,\ldots,dx_n>$, a prime ideal $P \subset R$ and a $P$-primary ideal. When this method is applied we obtain a finite list of differential operators $L_1,\ldots,L_m \in D$ such that $$ Q = \{ f \,\in\, R\, \mid\, L_i\, \bullet\, f\, \in P \, \forall 1 \le i \le m \}. $$ We say that $\{L_1,\ldots,L_m\}$ is a set Noetherian operators for the primary ideal $Q$. In the output of the algorithm we always have that $m$ (the number of Noetherian operators) is equal to the multiplicity of $Q$ over the prime ideal $P$.

i1 : R=QQ[x_1,x_2,x_3,x_4]

o1 = R

o1 : PolynomialRing
i2 : Q = ideal(x_1^2,x_1*x_2,x_1*x_3,x_1*x_4-x_3^2+x_1,x_3^2*x_4-x_2^2,x_3^2*x_4-x_3^2-x_2*x_3+2*x_1)

             2                 2               2      2   2             2
o2 = ideal (x , x x , x x , - x  + x x  + x , x x  - x , x x  - x x  - x  +
             1   1 2   1 3     3    1 4    1   3 4    2   3 4    2 3    3  
     ------------------------------------------------------------------------
     2x )
       1

o2 : Ideal of R
i3 : isPrimary Q

o3 = true
i4 : noetherianOperators(Q, Strategy => "PunctualHilbert")

                        2           2      2                              2
o4 = {1, dx_3, dx_2, (2x  + 2x )dx_2  + (4x  + 4)dx_2*dx_3 + (2x  + 2)dx_3  +
                        4     4            4                    4
     ------------------------------------------------------------------------
     4*dx_1}

o4 : List

Ways to use noetherianOperators :

For the programmer

The object noetherianOperators is a method function with options.