Fixed typo in Lebesgue lemma.

src/measure/lebesgue-integral/non-negative.tex

@@ -25,7 +25,7 @@
 \label{lemma:lebesgue-non-negative-strict}
     Let $(X, \cm, \mu)$ be a measure space and $f \in \mathcal{L}^+(X, \cm)$. 
     \begin{enumerate}
-        \item For each $\phi \in \Sigma^+(X, \cm)$, denote $\phi \le_u f$ if there exists $\delta > 0$ such that $\phi + \delta \ge f$ on $\bracs{\phi > 0}$, then
+        \item For each $\phi \in \Sigma^+(X, \cm)$, denote $\phi \le_u f$ if there exists $\delta > 0$ such that $\phi + \delta \le f$ on $\bracs{\phi > 0}$, then
         \[
         \int f d\mu = \sup\bracs{\int \phi d\mu \bigg | \phi \in \Sigma^+(X, \cm), \phi \le_u f}
         \]