diff --git a/main.tex b/main.tex index 66bf0689d0609e685c94406427f658bd8ebca03e..edf57c801e5d7e1beb7f93e3801cdfb28878ed2f 100644 --- a/main.tex +++ b/main.tex @@ -562,16 +562,36 @@ are trying to solve for. Fix a Chern character $v$ with positive rank, $\Delta(v) \geq 0$, and $\beta_{-}(v) \in \QQ$. -The goal is to find all pseudo-semistabilizers $u=(r,c\ell,d\ell^2)$ +The goal is to find all pseudo-semistabilizers $u$ which give circular pseudo-walls containing some fixed point $P\in\Theta_v^-$. With the added restriction that $u$ `destabilizes' $v$ moving `inwards', that is, -$\nu(u)>\nu(v)$ inside the circular pseudo-wall -(`outward' destabilizers can be recovered as $v-u$). - +$\nu(u)>\nu(v)$ inside the circular pseudo-wall. +\end{problem} This will give all pseudo-walls between the chamber corresponding to Gieseker stability and the stability condition corresponding to $P$. -\end{problem} +The purpose of the final `direction' condition is because, up to that point, +semistabilizers are not distinguished from their corresponding quotients: +Suppose $E\hookrightarrow F\twoheadrightarrow G$, then the tilt slopes +$\nu_{\alpha,\beta}$ +are strictly increasing, strictly decreasing, or equal across the short exact +sequence (consequence of the see-saw principle). +In this case, $\chern(E)$ is a pseudo-semistabilizer of $\chern(F)$, if and +only if $\chern(G)$ is a pseudo-semistabilizer of $\chern(F)$. +The numerical inequalities in the definition for pseudo-semistabilizer cannot +tell which of $E$ or $G$ is the subobject. +However what can be distinguished is the direction across the wall that +$\chern(E)$ or $\chern(G)$ destabilizes $\chern(F)$ +(they will each destabilize in the opposite direction to the other). +The `inwards' semistabilizers are preferred because we are moving from a +typically more familiar chamber +(the stable objects of Chern character $v$ in the outside chamber will only be +Gieseker stable sheaves). + +Also note that this last restriction does not remove any pseudo-walls found, +and if we do want to recover `outwards' semistabilizers, we can simply take +$v-u$ for each solution $u$ of the problem. + \begin{problem}[all `left' pseudo-walls] \label{problem:problem-statement-2}