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isdFactorization -- Checks if the differentials of a factorization compose to a scalar multiple of the identity

Description

This method checks if the differentials of a factorization compose to a scalar multiple of the identity. It returns a sequence where the first element is a boolean value indicating whether the factorization is well-defined, and the second element is the scalar multiple if it exists, otherwise it outputs no potential.

This check is distinct from isWellDefined for factorizations, since it does not do any other checks for well-definedness except for checking the differentials compose to a scalar multiple of the identity.

i1 : Q = ZZ/101[x_1..x_3];
i2 : X = ZZdfactorization {x_1, x_2 , x_3}

      1      1      1      1
o2 = Q  <-- Q  <-- Q  <-- Q
                           
     0      1      2      0

o2 : ZZdFactorization
i3 : isdFactorization(X)

o3 = (true, x x x )
             1 2 3

o3 : Sequence
i4 : f = x_1^3 + x_2^3 + x_3^3;
i5 : X2 = randomTailMF(f, 2, 4, 2)

      4      4      4
o5 = Q  <-- Q  <-- Q
                    
     0      1      0

o5 : ZZdFactorization
i6 : X2.dd

          4                                                                                                                                                                                        4
o6 = 1 : Q  <------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ Q  : 0
               {3} | 47x_2^2+8x_2x_3+14x_3^2 12x_2^2+46x_2x_3+17x_3^2 x_1^2+45x_1x_2+50x_2^2+35x_1x_3-38x_2x_3-37x_3^2 -4x_1x_2^2-11x_2^3-9x_1x_2x_3-41x_2^2x_3+19x_1x_3^2+28x_2x_3^2-43x_3^3 |
               {4} | -x_2-25x_3              x_1-46x_2+17x_3          2x_1+33x_2+28x_3                                 20x_1x_2+12x_2^2-8x_1x_3-13x_2x_3+43x_3^2                              |
               {4} | x_1-49x_2-34x_3         9x_1-5x_2-6x_3           12x_1+24x_2+27x_3                                -20x_1^2+45x_1x_2-13x_2^2+17x_1x_3+46x_2x_3-42x_3^2                    |
               {4} | x_1+14x_2+26x_3         9x_1-43x_2-50x_3         12x_1-26x_2-17x_3                                9x_1x_2-48x_2^2+17x_1x_3-32x_2x_3-6x_3^2                               |

          4                                                                                                                                                                               4
     0 : Q  <--------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Q  : 1
               {2} | 6x_1-50x_2-35x_3  -9x_1^2+38x_1x_2+32x_2^2+38x_1x_3-42x_2x_3-29x_3^2 47x_1x_2-23x_2^2-41x_1x_3+15x_2x_3+10x_3^2 x_1^2+31x_1x_2+32x_2^2-8x_1x_3+22x_2x_3-27x_3^2 |
               {2} | -2x_1-29x_2+24x_3 x_1^2+37x_1x_2+10x_2^2-40x_1x_3+44x_2x_3-31x_3^2   x_1x_2+15x_2^2+40x_1x_3-26x_2x_3-13x_3^2   -37x_2^2-15x_1x_3-17x_3^2                       |
               {2} | x_1-45x_2-35x_3   7x_2^2+26x_2x_3+8x_3^2                             20x_2^2+45x_2x_3+6x_3^2                    34x_2^2+48x_2x_3-20x_3^2                        |
               {3} | 0                 5x_2+9x_3                                          5x_1+9x_2                                  -5x_1+3x_2-3x_3                                 |

o6 : ZZdFactorizationMap
i7 : isdFactorization X2

             3    3    3
o7 = (true, x  + x  + x )
             1    2    3

o7 : Sequence
i8 : randomLinearMF(2,Q)

      32      32      32
o8 = Q   <-- Q   <-- Q
                      
     0       1       0

o8 : ZZdFactorization
i9 : isdFactorization oo

              2               2                        2
o9 = (true, 7x  + 15x x  + 39x  - 23x x  + 43x x  - 17x )
              1      1 2      2      1 3      2 3      3

o9 : Sequence
i10 : L = linearMF(f, t) --must specify root of unity t for larger period

      /   Q[t]   \9     /   Q[t]   \9     /   Q[t]   \9     /   Q[t]   \9
o10 = |----------|  <-- |----------|  <-- |----------|  <-- |----------|
      | 2        |      | 2        |      | 2        |      | 2        |
      \t  + t + 1/      \t  + t + 1/      \t  + t + 1/      \t  + t + 1/
                                                             
      0                 1                 2                 0

o10 : ZZdFactorization
i11 : isdFactorization L

              3    3    3
o11 = (true, x  + x  + x )
              1    2    3

o11 : Sequence
i12 : L.dd

          /   Q[t]   \9                                                                                      /   Q[t]   \9
o12 = 2 : |----------|  <----------------------------------------------------------------------------------- |----------|  : 0
          | 2        |     {0, 3} | x_3 0    0         x_2  x_1  0         0         0         0         |   | 2        |
          \t  + t + 1/     {0, 3} | 0   x_3  0         0    x_2t x_1       0         0         0         |   \t  + t + 1/
                           {0, 3} | 0   0    x_3       x_1  0    -x_2t-x_2 0         0         0         |
                           {0, 3} | 0   0    0         x_3t 0    0         x_2       x_1       0         |
                           {0, 3} | 0   0    0         0    x_3t 0         0         x_2t      x_1       |
                           {0, 3} | 0   0    0         0    0    x_3t      x_1       0         -x_2t-x_2 |
                           {0, 3} | x_2 x_1  0         0    0    0         -x_3t-x_3 0         0         |
                           {0, 3} | 0   x_2t x_1       0    0    0         0         -x_3t-x_3 0         |
                           {0, 3} | x_1 0    -x_2t-x_2 0    0    0         0         0         -x_3t-x_3 |

          /   Q[t]   \9                                                                                      /   Q[t]   \9
      0 : |----------|  <----------------------------------------------------------------------------------- |----------|  : 1
          | 2        |     {0, 3} | x_3 0    0         x_2  x_1  0         0         0         0         |   | 2        |
          \t  + t + 1/     {0, 3} | 0   x_3  0         0    x_2t x_1       0         0         0         |   \t  + t + 1/
                           {0, 3} | 0   0    x_3       x_1  0    -x_2t-x_2 0         0         0         |
                           {0, 3} | 0   0    0         x_3t 0    0         x_2       x_1       0         |
                           {0, 3} | 0   0    0         0    x_3t 0         0         x_2t      x_1       |
                           {0, 3} | 0   0    0         0    0    x_3t      x_1       0         -x_2t-x_2 |
                           {0, 3} | x_2 x_1  0         0    0    0         -x_3t-x_3 0         0         |
                           {0, 3} | 0   x_2t x_1       0    0    0         0         -x_3t-x_3 0         |
                           {0, 3} | x_1 0    -x_2t-x_2 0    0    0         0         0         -x_3t-x_3 |

          /   Q[t]   \9                                                                                      /   Q[t]   \9
      1 : |----------|  <----------------------------------------------------------------------------------- |----------|  : 2
          | 2        |     {0, 3} | x_3 0    0         x_2  x_1  0         0         0         0         |   | 2        |
          \t  + t + 1/     {0, 3} | 0   x_3  0         0    x_2t x_1       0         0         0         |   \t  + t + 1/
                           {0, 3} | 0   0    x_3       x_1  0    -x_2t-x_2 0         0         0         |
                           {0, 3} | 0   0    0         x_3t 0    0         x_2       x_1       0         |
                           {0, 3} | 0   0    0         0    x_3t 0         0         x_2t      x_1       |
                           {0, 3} | 0   0    0         0    0    x_3t      x_1       0         -x_2t-x_2 |
                           {0, 3} | x_2 x_1  0         0    0    0         -x_3t-x_3 0         0         |
                           {0, 3} | 0   x_2t x_1       0    0    0         0         -x_3t-x_3 0         |
                           {0, 3} | x_1 0    -x_2t-x_2 0    0    0         0         0         -x_3t-x_3 |

o12 : ZZdFactorizationMap
i13 : L.dd^3

          /   Q[t]   \9                                                                                                                                                                                   /   Q[t]   \9
o13 = 0 : |----------|  <-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |----------|  : 0
          | 2        |     {0, 3} | x_1^3+x_2^3+x_3^3 0                 0                 0                 0                 0                 0                 0                 0                 |   | 2        |
          \t  + t + 1/     {0, 3} | 0                 x_1^3+x_2^3+x_3^3 0                 0                 0                 0                 0                 0                 0                 |   \t  + t + 1/
                           {0, 3} | 0                 0                 x_1^3+x_2^3+x_3^3 0                 0                 0                 0                 0                 0                 |
                           {0, 3} | 0                 0                 0                 x_1^3+x_2^3+x_3^3 0                 0                 0                 0                 0                 |
                           {0, 3} | 0                 0                 0                 0                 x_1^3+x_2^3+x_3^3 0                 0                 0                 0                 |
                           {0, 3} | 0                 0                 0                 0                 0                 x_1^3+x_2^3+x_3^3 0                 0                 0                 |
                           {0, 3} | 0                 0                 0                 0                 0                 0                 x_1^3+x_2^3+x_3^3 0                 0                 |
                           {0, 3} | 0                 0                 0                 0                 0                 0                 0                 x_1^3+x_2^3+x_3^3 0                 |
                           {0, 3} | 0                 0                 0                 0                 0                 0                 0                 0                 x_1^3+x_2^3+x_3^3 |

          /   Q[t]   \9                                                                                                                                                                                   /   Q[t]   \9
      1 : |----------|  <-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |----------|  : 1
          | 2        |     {0, 3} | x_1^3+x_2^3+x_3^3 0                 0                 0                 0                 0                 0                 0                 0                 |   | 2        |
          \t  + t + 1/     {0, 3} | 0                 x_1^3+x_2^3+x_3^3 0                 0                 0                 0                 0                 0                 0                 |   \t  + t + 1/
                           {0, 3} | 0                 0                 x_1^3+x_2^3+x_3^3 0                 0                 0                 0                 0                 0                 |
                           {0, 3} | 0                 0                 0                 x_1^3+x_2^3+x_3^3 0                 0                 0                 0                 0                 |
                           {0, 3} | 0                 0                 0                 0                 x_1^3+x_2^3+x_3^3 0                 0                 0                 0                 |
                           {0, 3} | 0                 0                 0                 0                 0                 x_1^3+x_2^3+x_3^3 0                 0                 0                 |
                           {0, 3} | 0                 0                 0                 0                 0                 0                 x_1^3+x_2^3+x_3^3 0                 0                 |
                           {0, 3} | 0                 0                 0                 0                 0                 0                 0                 x_1^3+x_2^3+x_3^3 0                 |
                           {0, 3} | 0                 0                 0                 0                 0                 0                 0                 0                 x_1^3+x_2^3+x_3^3 |

          /   Q[t]   \9                                                                                                                                                                                   /   Q[t]   \9
      2 : |----------|  <-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |----------|  : 2
          | 2        |     {0, 3} | x_1^3+x_2^3+x_3^3 0                 0                 0                 0                 0                 0                 0                 0                 |   | 2        |
          \t  + t + 1/     {0, 3} | 0                 x_1^3+x_2^3+x_3^3 0                 0                 0                 0                 0                 0                 0                 |   \t  + t + 1/
                           {0, 3} | 0                 0                 x_1^3+x_2^3+x_3^3 0                 0                 0                 0                 0                 0                 |
                           {0, 3} | 0                 0                 0                 x_1^3+x_2^3+x_3^3 0                 0                 0                 0                 0                 |
                           {0, 3} | 0                 0                 0                 0                 x_1^3+x_2^3+x_3^3 0                 0                 0                 0                 |
                           {0, 3} | 0                 0                 0                 0                 0                 x_1^3+x_2^3+x_3^3 0                 0                 0                 |
                           {0, 3} | 0                 0                 0                 0                 0                 0                 x_1^3+x_2^3+x_3^3 0                 0                 |
                           {0, 3} | 0                 0                 0                 0                 0                 0                 0                 x_1^3+x_2^3+x_3^3 0                 |
                           {0, 3} | 0                 0                 0                 0                 0                 0                 0                 0                 x_1^3+x_2^3+x_3^3 |

o13 : ZZdFactorizationMap

Caveat

This command is distinct from isWellDefined, since it only checks if the differentials compose to be a scalar multiple of the identity.

See also

Ways to use isdFactorization:

  • isdFactorization(ZZdFactorization)

For the programmer

The object isdFactorization is a method function.


The source of this document is in MatrixFactorizations/MatrixFactorizationsDOC.m2:780:0.