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RationalMaps :: mapOntoImage

mapOntoImage -- Given a map of rings, correspoing to X mapping to Y, this returns the map of rings corresponding to X mapping to f(X).

Synopsis

Description

This function is really simple, given $S \to R$, this just returns $S/kernel \to R$.

i1 : R = QQ[x,y];
i2 : S = QQ[a,b,c];
i3 : f = map(R, S, {x^2, x*y, y^2});

o3 : RingMap R <--- S
i4 : mapOntoImage(f)

                 S       2        2
o4 = map (R, --------, {x , x*y, y })
              2
             b  - a*c

                        S
o4 : RingMap R <--- --------
                     2
                    b  - a*c
i5 : mapOntoImage(R,S,{x^2,x*y,y^2})

                 S       2        2
o5 = map (R, --------, {x , x*y, y })
              2
             b  - a*c

                        S
o5 : RingMap R <--- --------
                     2
                    b  - a*c

Ways to use mapOntoImage :

For the programmer

The object mapOntoImage is a method function with options.