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Commit a579508c authored by Luke Naylor's avatar Luke Naylor
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Start leading onto part with tighter bounds

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......@@ -23,7 +23,7 @@
\newcommand{\centralcharge}{\mathcal{Z}}
\newcommand{\minorheading}[1]{{\noindent\normalfont\normalsize\bfseries #1}}
\newtheorem{rmax_with_uniform_eps}{Theorem}[section]
\newtheorem{theorem}{Theorem}[section]
\begin{document}
......@@ -787,6 +787,13 @@ Some of the details around the associated numerics are explored next.
The strategy here is similar to what was shown in (sect \ref{sec:twisted-chern}),
% ref to Schmidt?
\begin{sagesilent}
var("a_F b_q n") # Define symbols introduce for values of beta and q
beta_value_expr = (beta == a_F/n)
q_value_expr = (q == b_q/n)
\end{sagesilent}
\renewcommand{\aa}{{a_F}}
\newcommand{\bb}{{b_q}}
Suppose $\beta = \frac{\aa}{n}$ for some coprime $n \in \NN,\aa \in \ZZ$.
......@@ -799,23 +806,6 @@ Then fix a value of $q$:
\cap [0, \chern_1^{\beta}(F)]
\end{equation}
as noted at the beginning of this section (\ref{sec:refinement}).
Firstly, we only consider $r$-values for which $c:=\chern_1(E)$ is integral:
\begin{sagesilent}
var("a_F b_q n") # Define symbols introduce for values of beta and q
beta_value_expr = (beta == a_F/n)
q_value_expr = (q == b_q/n)
\end{sagesilent}
\begin{equation}
c =
\sage{c_in_terms_of_q.subs([q_value_expr,beta_value_expr])}
\in \ZZ
\end{equation}
\noindent
That is, $r \equiv -\aa^{-1}\bb$ mod $n$ ($\aa$ is coprime to
$n$, and so invertible mod $n$).
Substituting the current values of $q$ and $\beta$ into the condition for the
radius of the pseudo-wall being positive
......@@ -832,7 +822,8 @@ radius of the pseudo-wall being positive
\frac{1}{2n^2}\ZZ
\end{equation}
\begin{rmax_with_uniform_eps}[Bound on $r$ \#1]
\begin{theorem}[Bound on $r$ \#1]
\label{thm:rmax_with_uniform_eps}
Let $v = (R,C,D)$ be a fixed Chern character. Then the ranks of the
pseudo-semistabilizers for $v$ are bounded above by the following expression.
......@@ -853,7 +844,7 @@ radius of the pseudo-wall being positive
\right)
\right\}
\end{align*}
\end{rmax_with_uniform_eps}
\end{theorem}
\begin{proof}
......@@ -945,8 +936,41 @@ for $\epsilon$ gives the result.
\end{proof}
%% TODO simplified expression for rmax by predicting which q gives rmax
%% refinements using specific values of q and beta
This bound can be refined a bit more by considering restrictions from the
possible values that $r$ take.
Furthermore, the proof of theorem \ref{thm:rmax_with_uniform_eps} uses the fact
that, given an element of $\frac{1}{2n^2}\ZZ$, the closest non-equal element of
$\frac{1}{m}\ZZ$ is at least $\frac{1}{\lcm(m,2n^2)}$ away. However this a
conservative estimate, and a larger gap can sometimes be guaranteed if we know
this value of $\frac{1}{2n^2}\ZZ$ explicitly.
The expressions that will follow will be a bit more complicated and have more
parts which depend on the values of $q$ and $\beta$, even their numerators
$\aa,\bb$ specifically. The upcoming theorem (TODO ref) is less useful as a
`nice' formula for a bound on the ranks of the pseudo-semistabilizers, but has a
purpose in the context of writing a computer program to find
pseudo-semistabilizers. Such a program would iterate through possible values of
$q$, then iterate through values of $r$ within the bounds (dependent on $q$),
which would then determine $c$, and then find the corresponding possible values
for $d$.
Firstly, we only consider $r$-values for which $c:=\chern_1(E)$ is integral:
\begin{equation}
c =
\sage{c_in_terms_of_q.subs([q_value_expr,beta_value_expr])}
\in \ZZ
\end{equation}
\noindent
That is, $r \equiv -\aa^{-1}\bb$ mod $n$ ($\aa$ is coprime to
$n$, and so invertible mod $n$).
\begin{sagesilent}
rhs_numerator = (
positive_radius_condition
......
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