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arXiv math/0512292math.AG
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光滑族的动机与三重循环

Motives of smooth families and cycles on threefolds

Vladimir Guletskii

摘要:

设X --> S是平滑曲线S上的光滑射影曲面族,使得一般纤维是一个具有Weil H^2的曲面,该曲面由因子和平凡H^1构成。证明了:若X/S的相对运动是有限维的,则系数在Q中的Chow群CH^2(X)是由一个多段垂直圈生成的,即,一维圈位于映射X -> S的闭纤维中.如果S是投影线P^1,则CH^2(X)是Q的n+1个拷贝的直和,其中n<=b_2,b_2是一般纤维的第二个贝蒂数。CH ^2(X)中的垂直生成元可以用上述H ^2的代数生成元的扩展来具体表示。我们还表明,这样的家庭是自然产生的蔓延表面C。

英文摘要:

Let X --> S be a smooth projective family of surfaces over a smooth curve S such that the generic fiber is a surface with Weil H^2 spanned by divisors and trivial H^1. We prove that if the relative motive of X/S is finite-dimensional the Chow group CH^2(X) with coefficients in Q is generated by a multisection and vertical cycles, i.e. one-dimensional cycles lying in closed fibers of the map X --> S. If S is the projective line P^1 then CH^2(X) is a direct sum of n+1 copies of Q where n<=b_2 and b_2 is the second Betti number of the generic fiber. Vertical generators in CH^2(X) can be concretely expressed in terms of spreads of algebraic generators of the above H^2. We also show where such families are naturally arising from by spreading out surfaces over C.

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