make inc induction slide more clear.

Author: wsc1

doc/slides/present.pdf

@@ -125,13 +125,13 @@ \subsection{Focus on Proofs}
 		Given $A$, find $P$:
 		\begin{align*}
 			I & \implies & P\\
-			P & \implies & \neg B\\
+			P & \implies & \neg b\\
 			A \wedge P \wedge T & \implies & P'
 		\end{align*}
 		Then update $A \leftarrow A \wedge P$.
 
 		In PDR/IC3, $A$ is CNF, $P$ is a clause which blocks
-		states than can reach $B$.
+		states than can reach $B$, indicated above as $b$.
 	\end{columns}
 \end{frame}