Whitney umbrella:
V = {x2-y2z = 0}
LIB "normal.lib";
ring r=0,(x,y,z),dp;
ideal i=x2-y2z;
list NN=normal(i);
def N=NN[1];
setring N;
normap;
=> normap[1]=T(1)*T(2)
=> normap[2]=T(1)
=> normap[3]=T(2)^2
Hence, the normalization map is:
(t1,
t2) -> (t1t2,
t1,
t22)
(real) picture via "parametrization"
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(real) picture via "implicitplot"
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