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Cremona :: graph(RingMap)

graph(RingMap) -- closure of the graph of a rational map

Synopsis

Description

i1 : phi = map(QQ[x_0..x_3],QQ[y_0..y_2],{-x_1^2+x_0*x_2,-x_1*x_2+x_0*x_3,-x_2^2+x_1*x_3})

                                               2                           2
o1 = map(QQ[x , x , x , x ],QQ[y , y , y ],{- x  + x x , - x x  + x x , - x  + x x })
             0   1   2   3      0   1   2      1    0 2     1 2    0 3     2    1 3

o1 : RingMap QQ[x , x , x , x ] <--- QQ[y , y , y ]
                 0   1   2   3           0   1   2
i2 : graph phi

               QQ[x , x , x , x , y , y , y ]                                           
                   0   1   2   3   0   1   2                                            
o2 = (map(----------------------------------------,QQ[x , x , x , x ],{x , x , x , x }),
          (x y  - x y  + x y , x y  - x y  + x y )     0   1   2   3    0   1   2   3   
            3 0    2 1    1 2   2 0    1 1    0 2                                       
     ----------------------------------------------------------------------------------------------------------------------------
              QQ[x , x , x , x , y , y , y ]
                  0   1   2   3   0   1   2
     map(----------------------------------------,QQ[y , y , y ],{y , y , y }))
         (x y  - x y  + x y , x y  - x y  + x y )     0   1   2    0   1   2
           3 0    2 1    1 2   2 0    1 1    0 2

o2 : Sequence

See also