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RAT Tally -- rational map defined by an effective divisor

Synopsis

Description

This is another way of calling rationalMap(MultiprojectiveVariety,Tally).

i1 : X = random(3,0_(PP_(ZZ/5)^2));

o1 : ProjectiveVariety, curve in PP^2
i2 : Y = PP_(ZZ/5)^4;

o2 : ProjectiveVariety, PP^4
i3 : H = Hom(X,Y);

o3 : Hom(X,Y)
i4 : D = tally toList(5:point X)

o4 = Tally{point of coordinates [1, -1, 1] => 5}

o4 : Tally
i5 : H D

o5 = multi-rational map consisting of one single rational map
     source variety: curve in PP^2 defined by a form of degree 3
     target variety: PP^4

o5 : MultirationalMap (rational map from X to Y)
i6 : show oo

o6 = -- multi-rational map --
                                ZZ
     source: subvariety of Proj(--[x , x , x ]) defined by
                                 5  0   1   2
             {
               3      2    3     2       2        2      2    3
              x  + x x  + x  + 2x x  - 2x x  - x x  + x x  + x
               0    0 1    1     0 2     1 2    0 2    1 2    2
             }
                  ZZ
     target: Proj(--[x , x , x , x , x ])
                   5  0   1   2   3   4
     -- rational map 1/1 -- 
     map 1/1, one of its representatives:
     {
       2 2         2 2    3 2    2 3     2 3       4      4    5
      x x x  - 2x x x  - x x  + x x  + 2x x  + 2x x  - x x  - x ,
       0 1 2     0 1 2    1 2    0 2     1 2     0 2    1 2    2
      
         3      2   2    3 2         3      4
      x x x  + x x x  - x x  - 2x x x  + x x ,
       0 1 2    0 1 2    1 2     0 1 2    1 2
      
         2 2    2 3    2 3       4    5
      x x x  + x x  - x x  - 2x x  + x ,
       0 1 2    0 2    1 2     0 2    2
      
       2 2      4       2   2    3 2        3       4
      x x x  + x x  + 2x x x  - x x  - x x x  + 2x x ,
       0 1 2    1 2     0 1 2    1 2    0 1 2     1 2
      
       2   2    3 2     2 3    2 3      4     5
      x x x  + x x  + 2x x  - x x  - x x  + 2x
       0 1 2    1 2     0 2    1 2    0 2     2
     }

See also

Ways to use this method: