Cartier divisor $mathbb{Q}$-trivial












5












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Let $X$ be a projective variety and $D$ a Cartier divisor on $X$ so that $Dsim_mathbb{Q} 0$. Is it true that $D$ is itself linearly equivalent to zero?










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  • $begingroup$
    Welcome the Mathematics Stack Exchange! A quick tour of the site (math.stackexchange.com/tour) will help you get the most of your time here.
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    – dantopa
    Dec 27 '18 at 23:09






  • 3




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    I'm not very familiar with the notion of Q rational Cartier divisors, but it seems like a nontrivial Cartier divisor D which is torsion in the Cartier class group should provide a counterexample, right?
    $endgroup$
    – Stahl
    Dec 27 '18 at 23:56


















5












$begingroup$


Let $X$ be a projective variety and $D$ a Cartier divisor on $X$ so that $Dsim_mathbb{Q} 0$. Is it true that $D$ is itself linearly equivalent to zero?










share|cite|improve this question









$endgroup$












  • $begingroup$
    Welcome the Mathematics Stack Exchange! A quick tour of the site (math.stackexchange.com/tour) will help you get the most of your time here.
    $endgroup$
    – dantopa
    Dec 27 '18 at 23:09






  • 3




    $begingroup$
    I'm not very familiar with the notion of Q rational Cartier divisors, but it seems like a nontrivial Cartier divisor D which is torsion in the Cartier class group should provide a counterexample, right?
    $endgroup$
    – Stahl
    Dec 27 '18 at 23:56
















5












5








5





$begingroup$


Let $X$ be a projective variety and $D$ a Cartier divisor on $X$ so that $Dsim_mathbb{Q} 0$. Is it true that $D$ is itself linearly equivalent to zero?










share|cite|improve this question









$endgroup$




Let $X$ be a projective variety and $D$ a Cartier divisor on $X$ so that $Dsim_mathbb{Q} 0$. Is it true that $D$ is itself linearly equivalent to zero?







algebraic-geometry commutative-algebra






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asked Dec 27 '18 at 23:02









WeiWei

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  • $begingroup$
    Welcome the Mathematics Stack Exchange! A quick tour of the site (math.stackexchange.com/tour) will help you get the most of your time here.
    $endgroup$
    – dantopa
    Dec 27 '18 at 23:09






  • 3




    $begingroup$
    I'm not very familiar with the notion of Q rational Cartier divisors, but it seems like a nontrivial Cartier divisor D which is torsion in the Cartier class group should provide a counterexample, right?
    $endgroup$
    – Stahl
    Dec 27 '18 at 23:56




















  • $begingroup$
    Welcome the Mathematics Stack Exchange! A quick tour of the site (math.stackexchange.com/tour) will help you get the most of your time here.
    $endgroup$
    – dantopa
    Dec 27 '18 at 23:09






  • 3




    $begingroup$
    I'm not very familiar with the notion of Q rational Cartier divisors, but it seems like a nontrivial Cartier divisor D which is torsion in the Cartier class group should provide a counterexample, right?
    $endgroup$
    – Stahl
    Dec 27 '18 at 23:56


















$begingroup$
Welcome the Mathematics Stack Exchange! A quick tour of the site (math.stackexchange.com/tour) will help you get the most of your time here.
$endgroup$
– dantopa
Dec 27 '18 at 23:09




$begingroup$
Welcome the Mathematics Stack Exchange! A quick tour of the site (math.stackexchange.com/tour) will help you get the most of your time here.
$endgroup$
– dantopa
Dec 27 '18 at 23:09




3




3




$begingroup$
I'm not very familiar with the notion of Q rational Cartier divisors, but it seems like a nontrivial Cartier divisor D which is torsion in the Cartier class group should provide a counterexample, right?
$endgroup$
– Stahl
Dec 27 '18 at 23:56






$begingroup$
I'm not very familiar with the notion of Q rational Cartier divisors, but it seems like a nontrivial Cartier divisor D which is torsion in the Cartier class group should provide a counterexample, right?
$endgroup$
– Stahl
Dec 27 '18 at 23:56












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