diff -r 432d027aa6f7 -r ae9ffbf979ff hws/hw04.tex
--- a/hws/hw04.tex	Sun Oct 12 12:50:16 2025 +0100
+++ b/hws/hw04.tex	Fri Oct 17 11:20:49 2025 +0100
@@ -261,7 +261,18 @@
   }
 
 \item Recall the functions \textit{nullable} and
-      \textit{zeroable}.  Define recursive functions
+      \textit{zeroable} from HW2. Define the cases of these
+      functions for the $r^{\{n\}}$ regular expression. Recall that the first 
+      function needs to satisfy the property $\textit{nullable}(r)$ iff $[]\in L(r)$ and
+      the second $\textit{zeroable}(r)$ iff $L(r) = \emptyset$
+
+  \solution{
+    $\textit{nullable}(r^{\{n\}}) \dn if n = 0 then true else \textit{nullable}(r)$
+
+    $\textit{zeroable}(r^{\{n\}}) \dn if n = 0 then false else \textit{zeroable}(r)$    
+  }    
+
+\item Define recursive functions
       \textit{atmostempty} (for regular expressions that match no
       string or only the empty string), \textit{somechars} (for
       regular expressions that match some non-empty string),