Skip to content
Snippets Groups Projects
Commit 8f28b259 authored by Luke Naylor's avatar Luke Naylor
Browse files

Remove all references to the Delta(u,v-u)>=0 condition

parent b3f3fc6a
No related branches found
No related tags found
No related merge requests found
......@@ -169,17 +169,11 @@ surfaces and $\PP^2$.
which has the same tilt slope as $v$: $\nu_{\alpha,\beta}(u) = \nu_{\alpha,\beta}(v)$.
\noindent
Furthermore the following Bogomolov-Gieseker inequalities are satisfied:
Furthermore the following inequalities are satisfied:
\begin{itemize}
\item $\Delta(u) \geq 0$
\item $\Delta(v-u) \geq 0$
\item $\Delta(u) + \Delta(v-u) \leq \Delta(v)$
\end{itemize}
\noindent
And finally these two conditions are satisfied:
\begin{itemize}
\item $\chern_1^{\beta}(u) \geq 0$
\item $\chern_1^{\beta}(v-u) \geq 0$
\item $0 \leq \chern_1^{\beta}(u) \leq \chern_1^{\beta}(v)$
\end{itemize}
Note $u$ does not need to be a Chern character of an actual sub-object of some
......@@ -498,7 +492,7 @@ Fixing attention on the only possible case (2), illustrated in Fig
\ref{fig:correct-hyperbol-intersection}.
$P$ is on the left of $V_{\pm u}$ (first part of consequence 2), so $u$ must
have positive rank (consequence 1)
to ensure that $\chern_1^{\beta{P}} \geq 0$ (since the pseudo-wall passed over
to ensure that $\chern_1^{\beta(P)} \geq 0$ (since the pseudo-wall passed over
$P$).
Furthermore, $P$ being on the left of $V_u$ implies
$\chern_1^{\beta{P}}(u) \geq 0$,
......@@ -845,85 +839,6 @@ This condition amounts to:
d &\geq \beta_{-}q + \frac{1}{2} \beta_{-}^2r
\end{align}
\subsubsection{
\texorpdfstring{
$\Delta(u,v-u) \geq 0$
}{
Δ(u,v-u) ≤ 0
}
}
\label{subsect-d-bound-bgmlv1}
Writing the condition in terms of the twisted chern characters
for $u$ and $v$ at $\beta$
($(r,\chern_1^{\beta}(u),\chern_2^{\beta}(u))$
and $(R-r,\chern_1^{\beta}(v-u),\chern_2^{\beta}(v-u))$) yields:
\begin{equation}
\label{eqn:bgmlv1-pt1}
(R-r)\chern_2^{\beta}(u)
\leq
\chern_1^{\beta}(u)\chern_1^{\beta}(v-u)
- r\chern_2^{\beta}(v-u)
\end{equation}
Which rearranges to (using additivity of $\chern_2^{\beta}$):
\begin{equation}
\label{eqn:bgmlv1-pt2}
(R-2r)\chern_2^{\beta}(u)
\leq
\chern_1^{\beta}(u)\chern_1^{\beta}(v-u)
- r\chern_2^{\beta}(v)
\end{equation}
With $u$ satisfying the condition given by equation \ref{eqn-cintermsofm},
we note that $\chern_1^{\beta}(u),\chern_1^{\beta}(v-u) \geq 0$.
In the special case with $P=(\beta_{-},0)$,
we have $\chern_2^{\beta_{-}}(v)=0$, and we can assume
equation $\chern_2^{\beta_{-}}(u)>0$ (eqn \ref{eqn:radius-cond-betamin})
in the context of our problem.
Finally, $r>0$ as per the statement of the problem, so the right-hand-side
of equation \ref{eqn:bgmlv1-pt1} is always greater than, or equal, to zero.
And so, when $P\coloneqq(\beta_{-},0)$, this condition $\Delta(u,v-u) \geq 0$ is
always satisfied when $2r \geq R$, provided that the other conditions of the
problem statement (\ref{subsect:problem-statement-2}) hold.
However, when $2r<R$, this condition does add potentially independent condition
of the others:
\begin{equation}
\label{eqn:bgmlv1-pt3}
\chern_2^{\beta}(u)
\leq
\frac{
\chern_1^{\beta}(u)\chern_1^{\beta}(v-u)
- r\chern_2^{\beta}(v)
}
{R-2r},
\qquad
2r<R
\end{equation}
Expressed in terms of $d$ and $q$:
\begin{equation}
\label{eqn:bgmlv1-pt4}
d
\leq
\beta_{-}q
+\frac{1}{2}{\beta_{-}}^2r
+
\frac{
q(\chern_1^{\beta}(v)-q)
- r\chern_2^{\beta}(v)
}
{R-2r},
\qquad
2r<R
\end{equation}
\subsubsection{
\texorpdfstring{
$\Delta(E) \geq 0$
......@@ -1203,17 +1118,6 @@ vertical wall (TODO as discussed in ref).
\phantom{+}& % to keep terms aligned
&\qquad\text{when\:} r > 0
\label{eqn:radiuscond_d_bound_betamin}
\\
d &\leq&
\frac{1}{2}{\beta}^2r
&+ \beta q
+&
\frac{
q(\chern_1^{\beta}(v)-q)
}
{R-2r},
&\qquad\text{when\:} 0 < r < \frac{R}{2}
\label{eqn:bgmlv1_d_bound_betamin}
\\
d &\leq&
\sage{bgmlv2_d_upperbound_linear_term}
......@@ -1279,18 +1183,6 @@ def plot_d_bound(
):
# Equations to plot imminently representing the bounds on d:
eq1 = (
(
beta^2*r/2
+ beta*q
+ q*(chb1v - q)/(R-2*r)
)
.subs(chb1v == v_example.twist(beta_min(v_example)).ch[1])
.subs(beta = beta_min(v_example))
.subs(q == q_example)
.subs(R == v_example.ch[0])
)
eq2 = (
bgmlv2_d_upperbound
.subs(R == v_example.ch[0])
......@@ -1337,13 +1229,6 @@ def plot_d_bound(
linestyle = "dotted",
legend_label=r"lower bound: $\mathrm{ch}_2^{\beta_{-}}(u)>0$"
)
+ plot(
eq1,
(r,0,v_example.ch[0]/2),
color='red',
linestyle = "dashed",
legend_label=r"upper bound: $\Delta(u,v) \geq 0$"
)
)
example_bounds_on_d_plot.ymin(ymin)
example_bounds_on_d_plot.ymax(ymax)
......
0% Loading or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment