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D.15.5.1 makeDivisor
Procedure from library divisors.lib (see divisors_lib).
- Usage:
- makeDivisor(I ,J); I = ideal, J = ideal.
- Assume:
- I and J are ideals in a qring Q of a smooth irreducible variety X
such that any ideal in Q satisfies the S2 condition.
- Return:
- a divisor on X
- Theory:
- The procedure will eliminate all components which are not of codimension 1.
The S2 condition requires that every proper nonzero principal ideal
has pure codimension 1.
Example:
| | LIB "divisors.lib";
ring r=31991,(x,y,z),dp;
ideal I = y^2*z - x*(x-z)*(x+3*z);
qring Q = std(I);
divisor P = makeDivisor(ideal(x,z),ideal(1));
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