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D.5.4.9 linearlyEquivalent

Procedure from library divisors.lib (see divisors_lib).

Usage:
linearlyEquivalent(A,B); A = divisor, B = divisor.

Assume:
A and B are divisors on X.

Return:
list if A and B a linearly equivalent and int 0 otherwise.

Theory:
Checks whether A-B is principle. If yes, returns a list L=(f,g) where A - B = (f/g).

Example:
 
LIB "divisors.lib";
==> Welcome to polymake version
==> Copyright (c) 1997-2015
==> Ewgenij Gawrilow, Michael Joswig (TU Darmstadt)
==> http://www.polymake.org
ring r=31991,(x,y,z),dp;
ideal I = y^2*z - x*(x-z)*(x+3*z);
qring Q = std(I);
divisor A = makeDivisor(ideal(x,z),ideal(1));
divisor B = makeDivisor(ideal(x,y),ideal(1));
linearlyEquivalent(A,B);
==> 0
linearlyEquivalent(multdivisor(2,A),multdivisor(2,B));
==> [1]:
==>    x
==> [2]:
==>    z