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Commit 4774b28c authored by Luke Naylor's avatar Luke Naylor
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Prove corrolary

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......@@ -1396,7 +1396,36 @@ r_upper_bound_all_q = (
\egroup
\end{corrolary}
%% TODO simplified expression for rmax by predicting which q gives rmax
\begin{proof}
\bgroup
\def\psi{\chern_1^{\beta}(F)}
\def\nu{\lcm(m,2n^2)}
\let\originalDelta\Delta
\renewcommand\Delta{{\psi^2}}
The ranks of the pseudo-semistabilizers for $v$ are bounded above by the
maximum over $q\in [0, \chern_1^{\beta}(F)]\cap \frac{1}{n}\ZZ$ of the
expression in theorem \ref{thm:rmax_with_uniform_eps}.
Noticing that the expression is a maximum of two quadratic functions in $q$:
\begin{equation*}
f_1(q):=\sage{r_upper_bound1.rhs()} \qquad
f_2(q):=\sage{r_upper_bound2.rhs()}
\end{equation*}
These have their minimums at $q=0$ and $q=\chern_1^{\beta}(F)$ respectively.
It suffices to find their intersection in
$q\in [0, \chern_1^{\beta}(F)]$, if it exists,
and evaluating on of the $f_i$ there.
The intersection exists, provided that
$f_1(\chern_1^{\beta}(F))>f_2(\chern_1^{\beta}(F))=R$,
or equivalently,
$R \leq \frac{1}{2}\lcm(m,2n^2){\chern_1^{\beta}(F)}^2$.
Setting $f_1(q)=f_2(q)$ yields
$q=\sage{q_sol.expand()}$.
And evaluating $f_1$ at this $q$-value gives:
$\sage{r_upper_bound_all_q.expand()}$.
Finally, noting that $\originalDelta(v)=\psi^2$, we get the bound as
stated in the corollary.
\egroup
\end{proof}
%% refinements using specific values of q and beta
......
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