diff --git a/main.tex b/main.tex index 8aed269e7a5ac254359f0605f92a2063690e94ee..40e3314c70dac6db0e29d035a80f5bd8ae75470e 100644 --- a/main.tex +++ b/main.tex @@ -135,11 +135,56 @@ for the rank of $E$: \section{Refinement} - +To get tighter bounds on the rank of destabilizers $E$ of some $F$ with some +fixed Chern character, we will need to consider each of the values which +$\chern_1^{\beta_{-}}(E)$ can take. +Doing this will allow us to eliminate possible values of $\chern_0(E)$ for which +each $\chern_1^{\beta_{-}}(E)$ leads to the failure of at least one of the inequalities. +As opposed to only eliminating possible values of $\chern_0(E)$ for which all +corresponding $\chern_1^{\beta_{-}}(E)$ fail one of the inequalities (which is what +was implicitly happening before). + +First, let's fix a Chern character for $F$, +$\chern(F) = (R,C,D)$, and consider the possible Chern characters +$\chern(E) = (r,c,d)$ of some semistabilizer $E$. + \begin{sagesilent} from pseudowalls import * + + v = Chern_Char(*var("R C D", domain="real")) + u = Chern_Char(*var("r c d", domain="real")) + + ts = stability.Tilt + + beta_min = min(map(lambda sol: sol.rhs(), + solve(ts(alpha=0).degree(v), ts().beta) + )) +\end{sagesilent} + +Here, we have $\beta_{-} = \sage{beta_min}$. +Recall [ref] that $\chern_1^{\beta_{-}}$ has fixed bounds in terms of +$\chern(F)$, and so we can write: + +\begin{equation} + \chern_1(E) = r\beta_{-} + m + \qquad 0 \leq m \leq \chern_1^{\beta_{-}}(F) +\end{equation} + +Furthermore, $\chern_1 \in \ZZ$ so we only need to consider +$m \in \frac{1}{n} \ZZ \cap [0, \chern_1^{\beta_{-}}(F)]$. +For the next subsections, we consider $m$ to be fixed with one of these values, +and we shall be varying $\chern_0(E) = r$ to see when certain inequalities fail. + +\begin{sagesilent} + c_lower_bound = -(ts(beta=beta_min).rank(u)/ts().alpha).expand() + c + + var("m", domain="real") + c_val = c_lower_bound + m \end{sagesilent} + + + \section{Conclusion} \end{document}