Minor compensation for beta tex redefinition

main.tex

@@ -1472,7 +1472,7 @@ stated in the corollary.
 \begin{example}[$v=(3, 2\ell, -2)$ on $\PP^2$]
 Just like in example \ref{exmpl:recurring-first}, take
 $\ell=c_1(\mathcal{O}(1))$ as the standard polarization on $\PP^2$, so
-that $m=2$, $\beta_-=\sage{recurring.b}$,
+that $m=2$, $\beta=\sage{recurring.b}$,
 giving $n=\sage{recurring.b.denominator()}$.
 
 \begin{sagesilent}