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Commit 00baee18 authored by Luke Naylor's avatar Luke Naylor
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Complete proof for Schmidt Bound

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...@@ -57,7 +57,7 @@ ...@@ -57,7 +57,7 @@
\put(0.72051844,0.18401749){\color[rgb]{0,0,0}\makebox(0,0)[lt]{\lineheight{1.25}\smash{\begin{tabular}[t]{l}\textbf{$\chern_0(u)$}\end{tabular}}}}% \put(0.72051844,0.18401749){\color[rgb]{0,0,0}\makebox(0,0)[lt]{\lineheight{1.25}\smash{\begin{tabular}[t]{l}\textbf{$\chern_0(u)$}\end{tabular}}}}%
\put(-0.00341324,0.92240317){\color[rgb]{0,0,0}\makebox(0,0)[lt]{\lineheight{1.25}\smash{\begin{tabular}[t]{l}\textbf{$\chern_2^{\beta_{-}}(u)$}\end{tabular}}}}% \put(-0.00341324,0.92240317){\color[rgb]{0,0,0}\makebox(0,0)[lt]{\lineheight{1.25}\smash{\begin{tabular}[t]{l}\textbf{$\chern_2^{\beta_{-}}(u)$}\end{tabular}}}}%
\put(0,0){\includegraphics[width=\unitlength,page=2]{schmidt-arg-diag.pdf}}% \put(0,0){\includegraphics[width=\unitlength,page=2]{schmidt-arg-diag.pdf}}%
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\put(0.35268151,0.97647054){\color[rgb]{0.6627451,0.11372549,0}\rotatebox{-44.62594593}{\makebox(0,0)[lt]{\lineheight{1.25}\smash{\begin{tabular}[t]{l}\textbf{$2\chern_0(u)\chern_2^{\beta_{-}}(u) \geq \chern_1^{\beta_{-}}(v)^2$}\end{tabular}}}}}% \put(0.35268151,0.97647054){\color[rgb]{0.6627451,0.11372549,0}\rotatebox{-44.62594593}{\makebox(0,0)[lt]{\lineheight{1.25}\smash{\begin{tabular}[t]{l}\textbf{$2\chern_0(u)\chern_2^{\beta_{-}}(u) \geq \chern_1^{\beta_{-}}(v)^2$}\end{tabular}}}}}%
\end{picture}% \end{picture}%
......
...@@ -284,7 +284,7 @@ ...@@ -284,7 +284,7 @@
</g> </g>
<text <text
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......
...@@ -40,12 +40,12 @@ The Bogomolov form applied to the twisted Chern character is the same as the ...@@ -40,12 +40,12 @@ The Bogomolov form applied to the twisted Chern character is the same as the
untwisted one. untwisted one.
\noindent \noindent
\begin{minipage}{0.59\linewidth} \begin{minipage}{0.57\linewidth}
So $0 \leq \Delta(u)$ (condition 2 from Corollary \ref{cor:num_test_prob2}) So $0 \leq \Delta(u)$ (condition 2 from Corollary \ref{cor:num_test_prob2})
yields: yields:
\begin{equation} \begin{equation}
\label{eqn-bgmlv-on-E} \label{eqn-bgmlv-on-E}
2\chern^\beta_0(u) \chern^\beta_2(u) \leq \chern^\beta_1(u)^2 2\chern_0(u) \chern^{\beta_{-}}_2(u) \leq \chern^{\beta_{-}}_1(u)^2
\end{equation} \end{equation}
\noindent \noindent
...@@ -58,9 +58,10 @@ untwisted one. ...@@ -58,9 +58,10 @@ untwisted one.
\end{equation} \end{equation}
\noindent \noindent
The restrictions on $\chern^{\beta_-}_0(u)$ and $\chern^{\beta_-}_2(v)$ The induced restrictions on possible pairs $\chern^{\beta_-}_0(u)$ and
is best seen with the following graph: $\chern^{\beta_-}_2(u)$,
% TODO: hyperbola restriction graph (shaded) as well as conditions 1 and 6 from Corollary \ref{cor:num_test_prob2}
are illustrated here on the right, with the invalid regions shaded.
\end{minipage} \end{minipage}
\hfill \hfill
\begin{minipage}{0.39\linewidth} \begin{minipage}{0.39\linewidth}
...@@ -71,40 +72,40 @@ untwisted one. ...@@ -71,40 +72,40 @@ untwisted one.
\subimport{../figures/}{schmidt-arg-diag.pdf_tex} \subimport{../figures/}{schmidt-arg-diag.pdf_tex}
} }
\end{center} \end{center}
\vspace{3pt}
\end{minipage} \end{minipage}
This is where the rationality of $\beta_{-}$ comes in. If Currently, the unshaded region in the diagram above, corresponding to possible
$\beta_{-} = \frac{a_v}{n}$ for some $a_v,n \in \ZZ$. values for $\chern_0(u)$ and $\chern^{\beta_{-}}_2(u)$ that satisfy the
Then $\chern^{\beta_-}_2(E) \in \frac{1}{\lcm(m,2n^2)}\ZZ$. currently considered restrictions, is unbounded.
In particular, since $\chern_2^{\beta_-}(E) > 0$ (by using $P=(\beta_-,0)$ in This is where the rationality of $\beta_{-}$ comes in.
lemma \ref{lem:pseudo_wall_numerical_tests}) we must also have If $\beta_{-} = \frac{a_v}{n}$ for some $a_v,n \in \ZZ$,
$\chern^{\beta_-}_2(E) \geq \frac{1}{\lcm(m,2n^2)}$, which then in turn gives a then $\chern^{\beta_-}_2(u) \in \frac{1}{\lcm(m,2n^2)}\ZZ$.
bound for the rank of $E$: In particular, since $\chern_2^{\beta_-}(u) > 0$ we must also have
$\chern^{\beta_-}_2(u) \geq \frac{1}{\lcm(m,2n^2)}$, which then in turn gives a
bound for the rank of $u$:
\begin{align} \begin{align}
\chern_0(E) &= \chern^{\beta_-}_0(E) \nonumber \\ \chern_0(u)
&\leq \frac{\lcm(m,2n^2) \chern^{\beta_-}_1(E)^2}{2} \nonumber \\ &\leq \frac{\chern^{\beta_-}_1(u)^2}{2\chern^{\beta_{-}}_2(u)} \nonumber \\
&= \frac{mn^2 \chern^{\beta_-}_1(F)^2}{\gcd(m,2n^2)} &\leq \frac{\lcm(m,2n^2) \chern^{\beta_-}_1(u)^2}{2} \nonumber \\
&= \frac{mn^2 \chern^{\beta_-}_1(u)^2}{\gcd(m,2n^2)}
\label{proof:first-bound-on-r} \label{proof:first-bound-on-r}
\end{align} \end{align}
\noindent
In fact Equation \ref{eqn-tilt-cat-cond} can be tightened slightly: Which we can then immediately bound using Equation \ref{eqn-tilt-cat-cond}.
we cannot have equality $\chern^{\beta_{-}}_1(E) = \chern^{\beta_{-}}_1(F)$ Alternatively, given that
otherwise we would have $\chern^{\beta_{-}}_1(G)=0$ for the quotient $G$. $\chern_1^{\beta_{-}}(u)$, $\chern_1^{\beta_{-}}(v)\in\frac{1}{n}\ZZ$,
This would imply $\mu(G)=\beta_{-}$, but since $\Theta_G$ is bounded above in the we can tighten this bound on $\chern_1^{\beta_{-}}(u)$ given by that Equation to:
upper-half plane by the assymptotes crossing the $\beta$-axis at $\pm45^\circ$ at \[
$\beta=\beta_{-}(v)$. So $\Theta_G$ cannot intersect $\Theta_v$ at any point n\chern^{\beta_{-}}_1(u) \leq n\chern^{\beta_{-}}_1(v) - 1
with $\alpha > 0$, so there is no point with $\nu(E)=\nu(F)=\nu(G)=0$, which would \]
have to hold at the top of the pseudo-wall if it were to exist. allowing us to bound the expression in Equation \ref{proof:first-bound-on-r} to
Therefore we must have a strict inequality the following:
$\chern^{\beta_{-}}_1(E) < \chern^{\beta_{-}}_1(F)$,
and since these are elements of $\frac{1}{n}\ZZ$, we can also conclude:
\[ \[
n\chern^{\beta_{-}}_1(E) \leq n\chern^{\beta_{-}}_1(F) - 1 \chern_0(u)
&\leq \frac{m\left(n \chern^{\beta_-}_1(v) - 1\right)^2}{\gcd(m,2n^2)}
\] \]
which then tightens the upper bound found for $\chern_0(E)$
in Equation \ref{proof:first-bound-on-r}
to the bound in the statement of the Lemma.
\end{proof} \end{proof}
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