diff --git a/Advanced/Stopping Problems/parts/0 probability.tex b/Advanced/Stopping Problems/parts/0 probability.tex
index 2ba3aec..3c3fde8 100644
--- a/Advanced/Stopping Problems/parts/0 probability.tex	
+++ b/Advanced/Stopping Problems/parts/0 probability.tex	
@@ -6,7 +6,7 @@ The elements of this set are called \textit{outcomes}. \par
 An \textit{event} is a set of outcomes (i.e, a subset of of $\Omega$).
 
 \definition{}
-A \textit{probability function} over a sample space $\Omega$ is a function $\mathcal{P}: P(\Omega) \to (0, 1)$ \par
+A \textit{probability function} over a sample space $\Omega$ is a function $\mathcal{P}: P(\Omega) \to [0, 1]$ \par
 that maps events to real numbers between 0 and 1. \par
 Any probability function has the following properties:
 \begin{itemize}