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Commit 963400e5 authored by Luke Naylor's avatar Luke Naylor
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Adjust plots and rephrase problem statement

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...@@ -38,6 +38,7 @@ sorting=ynt ...@@ -38,6 +38,7 @@ sorting=ynt
\newtheorem{lemma}{Lemma}[section] \newtheorem{lemma}{Lemma}[section]
\newtheorem{fact}{Fact}[section] \newtheorem{fact}{Fact}[section]
\newtheorem{example}{Example}[section] \newtheorem{example}{Example}[section]
\newtheorem{problem}{Problem Statement}
\begin{document} \begin{document}
...@@ -642,22 +643,33 @@ finding all pseudo-walls when $\beta_{-}\in\QQ$. In section [ref], a different ...@@ -642,22 +643,33 @@ finding all pseudo-walls when $\beta_{-}\in\QQ$. In section [ref], a different
algorithm will be presented making use of the later theorems in this article, algorithm will be presented making use of the later theorems in this article,
with the goal of cutting down the run time. with the goal of cutting down the run time.
\subsection*{Problem statement} \begin{problem}[sufficiently large `left' pseudo-walls]
\label{subsect:problem-statement} \label{problem:problem-statement-1}
Fix a Chern character $v$ with positive rank, $\Delta(v) \geq 0$, Fix a Chern character $v$ with positive rank, $\Delta(v) \geq 0$,
and $\beta_{-}(v) \in \QQ$. and $\beta_{-}(v) \in \QQ$.
The goal is to find all Chern characters $u=(r,c\ell,d\ell^2)$ which satisfy the The goal is to find all pseudo-semistabilizers $u=(r,c\ell,d\ell^2)$
conditions of lemma \ref{lem:pseudo_wall_numerical_tests} using which give circular pseudo-walls containing some fixed point
$P=(\beta_{-},0)$, $\chern_1^{\beta_{-}}(v-u)\geq 0$, as well as the Bogomolov inequalities: $P\in\Theta_v^-$.
$\Delta(u),\Delta(v-u) \geq 0$ and $\Delta(u)+\Delta(v-u) \leq \Delta(v)$. With the added restriction that $u$ `destabilizes' $v$ moving `inwards', that is,
We want to restrict our attention to pseudo-walls left of $V_v$ (condition (a) of $\nu(u)>\nu(v)$ inside the circular pseudo-wall
lemma), because this is the side of $V_v$ containing the chamber for Gieseker (`outward' destabilizers can be recovered as $v-u$).
stable objects, and the picture on the other side should be symmetric.
Condition (c) of the lemma is there to restrict to objects most likely to This will give all pseudo-walls between the chamber corresponding to Gieseker
semistabilizers of actual sheaves. The Chern characters which destabilize stability and the stability condition corresponding to $P$.
`outwards' can be recovered as $v-u$ for each solution $u$ to the current \end{problem}
problem.
\begin{problem}[all `left' pseudo-walls]
\label{problem:problem-statement-1}
Fix a Chern character $v$ with positive rank, $\Delta(v) \geq 0$,
and $\beta_{-}(v) \in \QQ$.
The goal is to find all solutions $u=(r,c\ell,d\ell^2)$
to problem \ref{problem:problem-statement-1} with the choice
$P=(\beta_{-},0)$.
This will give all circular pseudo-walls left of $V_v$.
\end{problem}
\subsection*{Algorithm} \subsection*{Algorithm}
...@@ -1310,14 +1322,14 @@ def plot_d_bound( ...@@ -1310,14 +1322,14 @@ def plot_d_bound(
\centering \centering
\begin{subfigure}{.45\textwidth} \begin{subfigure}{.45\textwidth}
\centering \centering
\sageplot[width=\linewidth]{plot_d_bound(v_example, 0)} \sageplot[width=\linewidth]{plot_d_bound(v_example, 0, ymin=-0.5)}
\caption{$q = 0$ (all bounds other than green coincide on line)} \caption{$q = 0$ (all bounds other than green coincide on line)}
\label{fig:d_bounds_xmpl_min_q} \label{fig:d_bounds_xmpl_min_q}
\end{subfigure}% \end{subfigure}%
\hfill \hfill
\begin{subfigure}{.45\textwidth} \begin{subfigure}{.45\textwidth}
\centering \centering
\sageplot[width=\linewidth]{plot_d_bound(v_example, 4, ymin=-3)} \sageplot[width=\linewidth]{plot_d_bound(v_example, 4, ymin=-3, ymax=3)}
\caption{$q = \chern^{\beta}(F)$ (all bounds other than blue coincide on line)} \caption{$q = \chern^{\beta}(F)$ (all bounds other than blue coincide on line)}
\label{fig:d_bounds_xmpl_max_q} \label{fig:d_bounds_xmpl_max_q}
\end{subfigure} \end{subfigure}
...@@ -1365,7 +1377,7 @@ Some of the details around the associated numerics are explored next. ...@@ -1365,7 +1377,7 @@ Some of the details around the associated numerics are explored next.
\centering \centering
\sageplot[ \sageplot[
width=\linewidth width=\linewidth
]{plot_d_bound(v_example, 2, ymax=6, ymin=-2, aspect_ratio=1)} ]{plot_d_bound(v_example, 2, ymax=4, ymin=-2, aspect_ratio=1)}
\caption{ \caption{
Bounds on $d:=\chern_2(E)$ in terms of $r:=\chern_0(E)$ for a fixed Bounds on $d:=\chern_2(E)$ in terms of $r:=\chern_0(E)$ for a fixed
value $\chern_1^{\beta}(F)/2$ of $q:=\chern_1^{\beta}(E)$. value $\chern_1^{\beta}(F)/2$ of $q:=\chern_1^{\beta}(E)$.
......
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