RegularChains[ConstructibleSetTools]
RationalMapImage
compute the image of a variety or a constructible set under a rational map
Calling Sequence
Parameters
Description
Examples
RationalMapImage(F, RM, R, S)
RationalMapImage(F, H, RM, R, S)
RationalMapImage(CS, RM, R, S)
F
-
list of polynomials
RM
a list of rational functions in R
R
a polynomial ring (source)
S
a polynomial ring (target)
H
CS
constructible set
The command RationalMapImage(F, RM, R, S) returns a constructible set cs which is the image of the variety VF under the rational map RM.
If H is specified, let W be the variety defined by the product of polynomials in H. The command RationalMapImage(F, H, RM, R, S) returns the image of the constructible set V-W under the rational map RM.
The command RationalMapImage(CS, RM, R, S) returns the image of the constructible set CS under the rational map RM.
Both rings R and S should be over the same ground field.
The variable sets of R and S should be disjoint.
The number of polynomials in RM is equal to the number of variables of ring S.
withRegularChains:
withConstructibleSetTools:
The following example is related to the tacnode curve.
S≔PolynomialRingt
S≔polynomial_ring
T≔PolynomialRingx,y
T≔polynomial_ring
F≔
RM≔t3−6t2+9t−22t4−16t3+40t2−32t+9,t2−4t+42t4−16t3+40t2−32t+9
cs≔RationalMapImageF,RM,S,T
cs≔constructible_set
Infocs,T
2x4−3yx2+y4−2y3+y2,y,10y+2x2+2y3−y2−y,964y6−480y5−6858y4−4328y3−888y2−72y−2x2−88y8+2104y7−2316y6−943y5+892y4+318y3+32y2+y,x,y−1,1,x,y,1
See Also
ConstructibleSet
Difference
MakePairwiseDisjoint
Projection
RegularChains
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