On Sat, Nov 10, 2018 at 9:08 PM Bill Page <[email protected]> wrote:
>
> On Sat, Nov 10, 2018 at 12:02 PM Waldek Hebisch
> <[email protected]> wrote:
> ...
> >
> > I have now implemented the lift part of Davenport-Caruso method.
> > You fetch code at:
> >
> > http://www.math.uni.wroc.pl/~hebisch/fricas/dcfact2.input
> > http://www.math.uni.wroc.pl/~hebisch/fricas/nc_ini04c.input
> >
> > As before, dcfact2.input is an actual routine, nc_ini04c.input
> > set up needed types.
...
>
> This looks very promising however I did find this apparent failure:
>
> (82) -> h3
>
>    (82)  - z y x + z x y + y z x - y x z - x z y + x y z
> Type: 
> XDistributedPolynomial(OrderedVariableList([x,y,z,w,x1,x2,x3,x4,x5]),Fraction(Integer))
>                                                    Time: 0.00 (OT) = 0.00 sec
> (83) -> dc_fact((3+x*z*y)*h3)
>
>    (83)
>    [
>        - 3 z y x + 3 z x y + 3 y z x - 3 y x z - 3 x z y + 3 x y z - x z y z 
> y x
>      +
>                           2           2
>        x z y z x y + x z y z x - x z y x z - x z y x z y + x z y x y z
>      ]
> Type: 
> List(XDistributedPolynomial(OrderedVariableList([x,y,z,w,x1,x2,x3,x4,x5]),Fraction(Integer)))
>                                                    Time: 0.00 (OT) = 0.00 sec

For comparison here is the output of Konrad Schrempf's program:

(1) -> )r nc_ini14.input
...
(52) -> h3 := x*y*z - x*z*y + z*x*y - z*y*x + y*z*x - y*x*z

   (52)
   AGGSET
      +1  - x  - z   0   - y   0    0    0 +    + 0 +
      |                                    |    |   |
      |    1    0    z    0    0    y    0 |    | 0 |
      |                                    |    |   |
      |         1   - x   0    y    0    0 |    | 0 |
      |                                    |    |   |
      |              1    0    0    0    y |    | 0 |
      |                                    |s = |   |
      |                   1   - z  - x   0 |    | 0 |
      |                                    |    |   |
      |                        1    0    x |    | 0 |
      |                                    |    |   |
      |                             1   - z|    | 0 |
      |                                    |    |   |
      +                                  1 +    +- 1+
  ,
       MR
  ,
       - z y x + z x y + y z x - y x z - x z y + x y z
Type: 
FreeDivisionAlgebra(OrderedVariableList([x,y,z,w,x1,x2,x3,x4,x5]),Fraction(Integer))
                           Time: 0.00 (IN) + 0.03 (EV) + 0.01 (OT) = 0.04 sec
(53) -> map(x+->x::XDP,factor((3+x*z*y)*h3))

   (53)  [3 + x z y, - z y x + z x y + y z x - y x z - x z y + x y z]
Type: 
List(XDistributedPolynomial(OrderedVariableList([x,y,z,w,x1,x2,x3,x4,x5]),Fraction(Integer)))
                           Time: 0.00 (IN) + 0.16 (EV) + 0.01 (OT) = 0.17 sec

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