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Nov 14, 2017 at 10:06 comment added var Actually I want this upper bound is uniform for all $X$ with fixed dimension and degree.
Nov 14, 2017 at 9:59 comment added var Oh, I don't think your argument about "constant $C$ doesn't depend on $X$ " is complete. Could you offer me more details about it?
Nov 13, 2017 at 0:58 history edited Vesselin Dimitrov CC BY-SA 3.0
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Nov 13, 2017 at 0:52 vote accept var
Nov 14, 2017 at 10:56
Nov 12, 2017 at 23:57 history undeleted Vesselin Dimitrov
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Nov 12, 2017 at 23:50 history edited Vesselin Dimitrov CC BY-SA 3.0
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Nov 12, 2017 at 21:36 comment added Vesselin Dimitrov @var: That is actually obvious: the bijection is just $Q \leftrightarrow g'^{-1} \cdot Q$.
Nov 12, 2017 at 17:13 comment added var Do you mean that the last two sets are isomorphism due to "Masser-Vaaler generalization of Northcott's asymptotic count"? Could you point out the refered theorem explicitly? Thank you.
Nov 12, 2017 at 9:40 history edited Vesselin Dimitrov CC BY-SA 3.0
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Nov 12, 2017 at 9:34 history edited Vesselin Dimitrov CC BY-SA 3.0
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Nov 12, 2017 at 9:28 comment added Vesselin Dimitrov @var: I edited the above. In my comment, I was trying to make the point that it is not really a problem that $Z$ can't be taken independently of $X$, due to the asymptotic lemma I formulated.
Nov 12, 2017 at 9:26 history edited Vesselin Dimitrov CC BY-SA 3.0
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Nov 12, 2017 at 8:32 comment added var Yes, the constant $C$ depends only on the center $Z$ of the projection, and the choosing of $Z$ is essentially the choosing of a rational point in $Gr(d+1, n)$ outside the Chow variety (or called Chow form) of $X$. For a fixed degree $X$, the height of such a rational point is at lest $\delta+1$, and this estimate is almost optimal. So I don't think the linear projection method works for this problem, since by this argument, the height of $Z$ is larger if $\delta$ is larger. For your add information, I don't know whether it works, could you provide me more information? Thank you.
Nov 12, 2017 at 4:34 comment added Vesselin Dimitrov Sorry, I wasn't very clear. The constant $C$ depends only on the center $Z$ of the linear projection: a linear subspace of dimension $n-d-1$ disjoint from $X$. In general, there needn't be such a fixed $Z$ if $\delta$ is unbounded. But choose any $Z$ (depending on $X$) and take $g$ a linear automorphism (over $K$) moving $Z$ to a fixed $\mathbb{P}_K^{n-d-1}$. Then use that $\# \{ H_K(\xi) \leq B \}$ and $\# \{ H_K(g \cdot \xi) \leq B \}$ have the same asymptotic count (where $\xi$ ranges over the points of $\mathbb{P}_K^d \subset \mathbb{P}_K^n$ with $[K(\xi):K] \leq D$). Does it make sense?
Nov 12, 2017 at 3:24 comment added var Do you know any method which can bound the constant as in the requiremen? Thank you very much.
Nov 12, 2017 at 3:15 comment added var I don't think your argument is complete. The key problem is the constant $C$ in your answer. I can only bound $C$ as $O(\delta^{n-d+1})$, which is far from the requirement. For the rational points case, I consider the corresponding affine cone, and count integral points by induction. For the hypersurfaces' case, I consider the polynomial directly.
Nov 11, 2017 at 20:41 history answered Vesselin Dimitrov CC BY-SA 3.0