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luke naylor latex documents
research
Max Destabilizer Rank
Commits
16c6732a
Commit
16c6732a
authored
1 year ago
by
Luke Naylor
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Tweak := to be more centered
parent
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main.tex
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25
View file @
16c6732a
...
...
@@ -11,6 +11,7 @@
\usepackage
{
minted
}
\usepackage
{
subcaption
}
\usepackage
{
cancel
}
\usepackage
{
mathtools
}
\usepackage
[]
{
breqn
}
\usepackage
[
backend=biber,
...
...
@@ -538,7 +539,7 @@ normal one. So $0 \leq \Delta(E)$ yields:
\begin{theorem}
[Bound on
$
r
$
- Benjamin Schmidt]
\label
{
thm:loose-bound-on-r
}
Given a Chern character
$
v
$
such that
$
\beta
_
-
:
=
\beta
_{
-
}
(
v
)
\in\QQ
$
, the rank
$
r
$
of
Given a Chern character
$
v
$
such that
$
\beta
_
-
\coloneqq
\beta
_{
-
}
(
v
)
\in\QQ
$
, the rank
$
r
$
of
any semistabilizer
$
E
$
of some
$
F
\in
\firsttilt
{
\beta
_
-
}$
with
$
\chern
(
F
)=
v
$
is
bounded above by:
...
...
@@ -748,8 +749,8 @@ was implicitly happening before).
First, let us fix a Chern character for
$
F
$
, and some semistabilizer
$
E
$
:
\begin{align}
v
&
:=
\chern
(F) = (R,C
\ell
,D
\ell
^
2)
\\
u
&
:=
\chern
(E) = (r,c
\ell
,d
\ell
^
2)
v
&
\coloneqq
\chern
(F) = (R,C
\ell
,D
\ell
^
2)
\\
u
&
\coloneqq
\chern
(E) = (r,c
\ell
,d
\ell
^
2)
\end{align}
\begin{sagesilent}
...
...
@@ -783,7 +784,7 @@ c_in_terms_of_q = c_lower_bound + q
\begin{equation}
\label
{
eqn-cintermsofm
}
c=
\chern
_
1(u) =
\sage
{
c
_
in
_
terms
_
of
_
q
}
\qquad
0
\leq
q
:=
\chern
_
1
^{
\beta
}
(u)
\leq
\chern
_
1
^{
\beta
}
(v)
\qquad
0
\leq
q
\coloneqq
\chern
_
1
^{
\beta
}
(u)
\leq
\chern
_
1
^{
\beta
}
(v)
\end{equation}
Furthermore,
$
\chern
_
1
\in
\ZZ
$
so we only need to consider
...
...
@@ -851,7 +852,7 @@ 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
:
=
(
\beta
_{
-
}
,
0
)
$
, this condition
$
\Delta
(
u,v
-
u
)
\geq
0
$
is
And so, when
$
P
\coloneqq
(
\beta
_{
-
}
,
0
)
$
, this condition
$
\Delta
(
u,v
-
u
)
\geq
0
$
is
always satisfied when
$
2
r
\geq
R
$
, provided that the other conditions of the
problem statement (
\ref
{
subsect:problem-statement
}
) hold.
...
...
@@ -1334,20 +1335,20 @@ def plot_d_bound(
\label
{
fig:d
_
bounds
_
xmpl
_
max
_
q
}
\end{subfigure}
\caption
{
Bounds on
$
d
:
=
\chern
_
2
(
E
)
$
in terms of
$
r
:
=
\chern
_
0
(
E
)
$
for fixed, extreme,
values of
$
q
:
=
\chern
_
1
^{
\beta
}
(
E
)
$
.
Bounds on
$
d
\coloneqq
\chern
_
2
(
E
)
$
in terms of
$
r
\coloneqq
\chern
_
0
(
E
)
$
for fixed, extreme,
values of
$
q
\coloneqq
\chern
_
1
^{
\beta
}
(
E
)
$
.
Where
$
\chern
(
F
)
=
(
3
,
2
,
-
2
)
$
.
}
\label
{
fig:d
_
bounds
_
xmpl
_
extrm
_
q
}
\end{figure}
Recalling that
$
q
:
=
\chern
^{
\beta
}_
1
(
E
)
\in
[
0
,
\chern
^{
\beta
}_
1
(
F
)]
$
,
Recalling that
$
q
\coloneqq
\chern
^{
\beta
}_
1
(
E
)
\in
[
0
,
\chern
^{
\beta
}_
1
(
F
)]
$
,
it is worth noting that the extreme values of
$
q
$
in this range lead to the
tightest bounds on
$
d
$
, as illustrated in figure
(
\ref
{
fig:d
_
bounds
_
xmpl
_
extrm
_
q
}
).
In fact, in each case, one of the weak upper bounds coincides with one of the
weak lower bounds, (implying no possible destabilizers
$
E
$
with
$
\chern
_
0
(
E
)=
:r>R:
=
\chern
_
0
(
F
)
$
for these
$
q
$
-values).
$
\chern
_
0
(
E
)=
\vcentcolon
r>R
\coloneqq
\chern
_
0
(
F
)
$
for these
$
q
$
-values).
This indeed happens in general since the right hand sides of
(eqn
\ref
{
eqn:bgmlv2
_
d
_
bound
_
betamin
}
) and
(eqn
\ref
{
eqn:positive
_
rad
_
d
_
bound
_
betamin
}
) match when
$
q
=
0
$
.
...
...
@@ -1356,7 +1357,7 @@ In the other case, $q=\chern^{\beta}_1(F)$, it is the right hand sides of
(eqn
\ref
{
eqn:positive
_
rad
_
d
_
bound
_
betamin
}
) which match.
The more generic case, when
$
0
< q
:
=
\chern
_
1
^{
\beta
}
(
E
)
<
\chern
_
1
^{
\beta
}
(
F
)
$
The more generic case, when
$
0
< q
\coloneqq
\chern
_
1
^{
\beta
}
(
E
)
<
\chern
_
1
^{
\beta
}
(
F
)
$
for the bounds on
$
d
$
in terms of
$
r
$
is illustrated in figure
(
\ref
{
fig:d
_
bounds
_
xmpl
_
gnrc
_
q
}
).
The question of whether there are pseudo-destabilizers of arbitrarily large
...
...
@@ -1379,8 +1380,8 @@ Some of the details around the associated numerics are explored next.
width=
\linewidth
]
{
plot
_
d
_
bound(v
_
example, 2, ymax=4, ymin=-2, aspect
_
ratio=1)
}
\caption
{
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
)
$
.
Bounds on
$
d
\coloneqq
\chern
_
2
(
E
)
$
in terms of
$
r
\coloneqq
\chern
_
0
(
E
)
$
for a fixed
value
$
\chern
_
1
^{
\beta
}
(
F
)/
2
$
of
$
q
\coloneqq
\chern
_
1
^{
\beta
}
(
E
)
$
.
Where
$
\chern
(
F
)
=
(
3
,
2
,
-
2
)
$
.
}
\label
{
fig:d
_
bounds
_
xmpl
_
gnrc
_
q
}
...
...
@@ -1399,7 +1400,7 @@ $(r,c,d)$ that satisfy all inequalities to give a pseudowall.
The strategy here is similar to what was shown in (sect
\ref
{
sec:twisted-chern
}
).
One specialization here is to use that
$
\ell
:
=
c
_
1
(
H
)
$
generates
$
NS
(
X
)
$
, so that
One specialization here is to use that
$
\ell
\coloneqq
c
_
1
(
H
)
$
generates
$
NS
(
X
)
$
, so that
in fact, any Chern character can be written as
$
\left
(
r,c
\ell
,
\frac
{
e
}{
2
}
\ell
^
2
\right
)
$
for
$
r,c,e
\in\ZZ
$
.
% ref to Schmidt?
...
...
@@ -1415,7 +1416,7 @@ q_value_expr = (q == b_q/n)
Suppose
$
\beta
=
\frac
{
\aa
}{
n
}$
for some coprime
$
n
\in
\NN
,
\aa
\in
\ZZ
$
.
Then fix a value of
$
q
$
:
\begin{equation}
q
:=
\chern
_
1
^{
\beta
}
(E)
q
\coloneqq
\chern
_
1
^{
\beta
}
(E)
=
\frac
{
\bb
}{
n
}
\in
\frac
{
1
}{
n
}
\ZZ
...
...
@@ -1530,7 +1531,7 @@ bounds_too_tight_condition2 = (
\sage
{
bgmlv2
_
d
_
upperbound
_
exp
_
term
}
,
\sage
{
bgmlv3
_
d
_
upperbound
_
exp
_
term
_
alt2
}
\right
)
\geq
\epsilon
:=
\frac
{
1
}{
2n
^
2
}
\geq
\epsilon
\coloneqq
\frac
{
1
}{
2n
^
2
}
\end{equation}
\egroup
...
...
@@ -1576,7 +1577,7 @@ r_upper_bound_all_q = (
\begin{corrolary}
[Bound on
$
r
$
\#
2]
\label
{
cor:direct
_
rmax
_
with
_
uniform
_
eps
}
Let
$
v
$
be a fixed Chern character and
$
R
:
=
\chern
_
0
(
v
)
\leq
n
^
2
\Delta
(
v
)
$
.
$
R
\coloneqq
\chern
_
0
(
v
)
\leq
n
^
2
\Delta
(
v
)
$
.
Then the ranks of the pseudo-semistabilizers for
$
v
$
are bounded above by the following expression.
...
...
@@ -1599,8 +1600,8 @@ maximum over $q\in [0, \chern_1^{\beta}(F)]$ 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.subs(kappa==1).rhs()
}
\qquad
f
_
2(q)
:=
\sage
{
r
_
upper
_
bound2.subs(kappa==1).rhs()
}
f
_
1(q)
\coloneqq
\sage
{
r
_
upper
_
bound1.subs(kappa==1).rhs()
}
\qquad
f
_
2(q)
\coloneqq
\sage
{
r
_
upper
_
bound2.subs(kappa==1).rhs()
}
\end{equation*}
These have their minimums at
$
q
=
0
$
and
$
q
=
\chern
_
1
^{
\beta
}
(
F
)
$
respectively.
It suffices to find their intersection in
...
...
@@ -1687,7 +1688,7 @@ which would then determine $c$, and then find the corresponding possible values
for
$
d
$
.
Firstly, we only need to consider
$
r
$
-values for which
$
c
:
=
\chern
_
1
(
E
)
$
is
Firstly, we only need to consider
$
r
$
-values for which
$
c
\coloneqq
\chern
_
1
(
E
)
$
is
integral:
\begin{equation}
...
...
@@ -1742,7 +1743,7 @@ proof of theorem \ref{thm:rmax_with_uniform_eps}:
Where
$
\epsilon
_{
v,q
}$
is defined as follows:
\begin{equation*}
\epsilon
_{
v,q
}
:=
\epsilon
_{
v,q
}
\coloneqq
\frac
{
k
_{
q
}}{
2n
^
2
}
\end{equation*}
with
$
k
_{
v,q
}$
being the least
$
k
\in\ZZ
_{
>
0
}$
satisfying
$
k
\equiv
-
\aa\bb
\mod
n
$
...
...
@@ -1800,7 +1801,7 @@ $\epsilon_{v,q}\geq\epsilon_v$, with equality when $k_{v,q}=1$.
\begin{theorem}
[Bound on
$
r
$
\#
3]
\label
{
thm:rmax
_
with
_
eps1
}
Let
$
v
$
be a fixed Chern character, with
$
\frac
{
a
_
v
}{
n
}
=
\beta
:
=
\beta
(
v
)
$
Let
$
v
$
be a fixed Chern character, with
$
\frac
{
a
_
v
}{
n
}
=
\beta
\coloneqq
\beta
(
v
)
$
rational and expressed in lowest terms.
Then the ranks
$
r
$
of the pseudo-semistabilizers
$
u
$
for
$
v
$
with
$
\chern
_
1
^
\beta
(
u
)
=
q
=
\frac
{
b
_
q
}{
n
}$
...
...
@@ -1837,8 +1838,8 @@ take $\ell=c_1(\mathcal{O}(1))$ as the standard polarization on $\PP^2$, so that
$
\beta
=
\sage
{
recurring.b
}$
, giving
$
n
=
\sage
{
recurring.b.denominator
()
}$
and
$
\chern
_
1
^{
\sage
{
recurring.b
}}
(
F
)
=
\sage
{
recurring.twisted.ch
[
1
]
}$
.
%% TODO transcode notebook code
The (non-exclusive) upper bounds for
$
r
:
=
\chern
_
0
(
u
)
$
of a tilt semistabilizer
$
u
$
of
$
v
$
in terms of the possible values for
$
q
:
=
\chern
_
1
^{
\beta
}
(
u
)
$
are as follows:
The (non-exclusive) upper bounds for
$
r
\coloneqq
\chern
_
0
(
u
)
$
of a tilt semistabilizer
$
u
$
of
$
v
$
in terms of the possible values for
$
q
\coloneqq
\chern
_
1
^{
\beta
}
(
u
)
$
are as follows:
\begin{sagesilent}
import numpy as np
...
...
@@ -1923,8 +1924,8 @@ possible values for $k_{v,q}$, in dfn/lemma \ref{lemdfn:epsilon_q}. This allows
for a larger possible difference between the bounds given by theorems
\ref
{
thm:rmax
_
with
_
uniform
_
eps
}
and
\ref
{
thm:rmax
_
with
_
eps1
}
, with the bound
from the second being up to
$
\sage
{
n
}$
smaller, for any given
$
q
$
value.
The (non-exclusive) upper bounds for
$
r
:
=
\chern
_
0
(
u
)
$
of a tilt semistabilizer
$
u
$
of
$
v
$
in terms of the first few smallest possible values for
$
q
:
=
\chern
_
1
^{
\beta
}
(
u
)
$
are as follows:
The (non-exclusive) upper bounds for
$
r
\coloneqq
\chern
_
0
(
u
)
$
of a tilt semistabilizer
$
u
$
of
$
v
$
in terms of the first few smallest possible values for
$
q
\coloneqq
\chern
_
1
^{
\beta
}
(
u
)
$
are as follows:
\begin{sagesilent}
qs, theorem2
_
bounds, theorem3
_
bounds = bound
_
comparisons(extravagant)
...
...
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