diff --git a/main.tex b/main.tex index 128ed83bb7ae7507cefbe737c32a27e883dd4d1f..b3a0f9f649ed2e1ee815a6038ddd2589dd980ff7 100644 --- a/main.tex +++ b/main.tex @@ -10,6 +10,7 @@ \newcommand{\QQ}{\mathbb{Q}} \newcommand{\ZZ}{\mathbb{Z}} +\newcommand{\RR}{\mathbb{R}} \newcommand{\chern}{\operatorname{ch}} \newcommand{\lcm}{\operatorname{lcm}} \newcommand{\gcd}{\operatorname{gcd}} @@ -28,12 +29,12 @@ Practical Methods for Finding Pseudowalls} \section{Introduction} -[ref] shows that for any $\beta_0 \in \QQ$, -the vertical line $\{\sigma_{\alpha,\beta_0} \colon \alpha \in \QQ_{>0}\}$ only +[ref] shows that for any rational $\beta_0$, +the vertical line $\{\sigma_{\alpha,\beta_0} \colon \alpha \in \RR_{>0}\}$ only intersects finitely many walls. A consequence of this is that if -$\beta_{-} \in \QQ$, then there can only be finitely many circular walls to the +$\beta_{-}$ is rational, then there can only be finitely many circular walls to the left of the vertical wall $\beta = \mu$. -On the other hand, when $\beta_{-} \not\in \QQ$, [ref] showed that there are +On the other hand, when $\beta_{-}$ is not rational, [ref] showed that there are infinitely many walls. This dichotomy does not only hold for real walls, realised by actual objects in @@ -43,11 +44,11 @@ which satisfy certain numerical conditions which would be satisfied by any real destabilizer, regardless of whether they are realised by actual elements of $\bddderived(X)$. -Since real walls are a subset of pseudowalls, the $\beta_{-} \not\in \QQ$ case +Since real walls are a subset of pseudowalls, the irrational $\beta_{-}$ case follows immediately from the corresponding case for real walls. -However, the $\beta_{-} \in \QQ$ case involves showing that the following +However, the rational $\beta_{-}$ case involves showing that the following conditions only admit finitely many solutions (despite the fact that the same -conditions admit infinitely many solutions when $\beta_{-} \not\in \QQ$). +conditions admit infinitely many solutions when $\beta_{-}$ is irrational). For a destabilizing sequence