"Source: Text/Geometry/Scheme.text";
"Line: 9199";
"Date: Thu Sep 25 14:47:45 2025";
"Main: Fri Sep 26 14:29:19 2025";
// original file: Text/Geometry/Scheme.text, line: 9199
// Example: H122E76 ()
print "Example: H122E76";
ei := GetEchoInput();
SetEchoInput(true);
P<x,y,z,t,u> := ProjectiveSpace(RationalField(), 4);
S := Surface(P,[z^2-z*t-y*u, y*z-x*t-z*t-y*u]);
p := S![0,0,0,0,1];
IsSingular(p);
l := Scheme(P,[y,z-t,x+z]); // l is a line thorugh p
l subset S; // and l lies in S
assert $1;
D := Divisor(S,Ideal(l));
IsCartier(D);
assert not $1;
SetEchoInput(ei);
