diff --git a/main.tex b/main.tex index 09ba6f52d0a86fb18d21a33977a136c1fbb32768..e64982bd5be5277d9ba16d2cd5b3888fb686b36d 100644 --- a/main.tex +++ b/main.tex @@ -77,6 +77,31 @@ Practical Methods for Narrowing Down Possible Walls} \section{Introduction} \label{sec:intro} +The theory of Bridgeland stability conditions \cite{BridgelandTom2007SCoT} on +complexes of sheaves was developed as a generalisation of stability for vector +bundles. The definition is most analoguous to Mumford stability, but is more +aware of the features that sheaves can have on spaces of dimension greater +than 1. Whilst also asymptotically matching up with Gieseker stability. +For K3 surfaces, explicit stability conditions were defined in +\cite{Bridgeland_StabK3}, and later shown to also be valid on other surfaces. + +The moduli spaces of stable objects of some fixed Chern character $v$ is +studied, as well as how they change as we vary the Bridgeland stability +condition. They in fact do not change over whole regions of the stability +space (called chambers), but do undergo changes as we cross `walls' in the +stability space. These are where there is some stable object $F$ of $v$ which +has a subobject who's slope overtakes the slope of $v$, making $F$ unstable +after crossing the wall. + +% NOTE: SURFACE SPACIALIZATION +% (come back to these when adjusting to general Picard rank 1) +In this document we concentrate on two surfaces: Principally polarized abelian +surfaces and the projective surface $\PP^2$. Although this can be generalised +for Picard rank 1 surfaces, the formulae will need adjusting. +The Bridgeland stability conditions (defined in \cite{Bridgeland_StabK3}) are +given by two parameters $\alpha \in \RR_{>0}$, $\beta \in \RR$, which will be +illustrated throughout this article with diagrams of the upper half plane. + It is well known that for any rational $\beta_0$, the vertical line $\{\sigma_{\alpha,\beta_0} \colon \alpha \in \RR_{>0}\}$ only intersects finitely many walls @@ -103,11 +128,11 @@ conditions only admit finitely many solutions (despite the fact that the same conditions admit infinitely many solutions when $\beta_{-}$ is irrational). -For a destabilizing sequence +For a semistabilizing sequence $E \hookrightarrow F \twoheadrightarrow G$ in $\mathcal{B}^\beta$ we have the following conditions. -There are some Bogomolov-Gieseker type inequalities: -$0 \leq \Delta(E), \Delta(G)$ and $\Delta(E) + \Delta(G) \leq \Delta(F)$. +There are some Bogomolov-Gieseker inequalities: +$0 \leq \Delta(E), \Delta(G)$. We also have a condition relating to the tilt category $\firsttilt\beta$: $0 \leq \chern^\beta_1(E) \leq \chern^\beta_1(F)$. Finally, there is a condition ensuring that the radius of the circular wall is @@ -663,7 +688,7 @@ stability and the stability condition corresponding to $P$. \end{problem} \begin{problem}[all `left' pseudo-walls] -\label{problem:problem-statement-1} +\label{problem:problem-statement-2} Fix a Chern character $v$ with positive rank, $\Delta(v) \geq 0$, and $\beta_{-}(v) \in \QQ$. @@ -856,7 +881,7 @@ 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}) hold. +problem statement (\ref{subsect:problem-statement-2}) hold. However, when $2r<R$, this condition does add potentially independent condition of the others: @@ -1397,7 +1422,7 @@ no possible solutions for $d$. At that point, there are no Chern characters $(r,c,d)$ that satisfy all inequalities to give a pseudowall. -\subsubsection{All Semistabilizers Left of Vertical Wall for Rational Beta min} +\subsubsection{All Semistabilizers Left of $V_v$ for Rational beta} The strategy here is similar to what was shown in (sect diff --git a/references.bib b/references.bib index 78f44248d3c9cae41f7e1de6e92b2cc699887378..6fbe7e3f91ed2f46da8042c24245ac354f2917d6 100644 --- a/references.bib +++ b/references.bib @@ -133,4 +133,31 @@ publisher = {Wiley}, title = {An introduction to the theory of numbers / Ivan Niven, Herbert S. Zuckerman.}, year = {1966}, -} \ No newline at end of file +} +@article{Bridgeland_StabK3, + author = {Tom Bridgeland}, + title = {{Stability conditions on $K3$ surfaces}}, + volume = {141}, + journal = {Duke Mathematical Journal}, + number = {2}, + publisher = {Duke University Press}, + pages = {241 -- 291}, + year = {2008}, + doi = {10.1215/S0012-7094-08-14122-5}, + URL = {https://doi.org/10.1215/S0012-7094-08-14122-5} +} +@article{BridgelandTom2007SCoT, + author = {Bridgeland, Tom}, + address = {PRINCETON}, + copyright = {Copyright 2007 Princeton University (Mathematics Department)}, + issn = {0003-486X}, + journal = {Annals of mathematics}, + keywords = {Algebra ; Exact sciences and technology ; General mathematics ; General, history and biography ; Homomorphisms ; Mathematics ; Morphisms ; Nitration ; Physical Sciences ; Quotients ; Real numbers ; Science & Technology ; Sciences and techniques of general use ; String theory ; Topological spaces ; Topology}, + language = {eng}, + number = {2}, + pages = {317-345}, + publisher = {Princeton University Press}, + title = {Stability Conditions on Triangulated Categories}, + volume = {166}, + year = {2007}, +}