2 files changed, 10 insertions, 4 deletions
diff --git a/chapter13/src/main/java/com/seaofnodes/simple/node/DivNode.java b/chapter13/src/main/java/com/seaofnodes/simple/node/DivNode.java
index a3845d89..e0c95019 100644
--- a/chapter13/src/main/java/com/seaofnodes/simple/node/DivNode.java
+++ b/chapter13/src/main/java/com/seaofnodes/simple/node/DivNode.java
@@ -32,7 +32,12 @@ public class DivNode extends Node {
     }
 
     @Override
-    public Node idealize() { return null; }
+    public Node idealize() {
+        // Div of 1.
+        if( in(2)._type.isConstant() && in(2)._type instanceof TypeInteger i && i.value()==1 )
+            return in(1);
+        return null;
+    }
 
     @Override Node copy(Node lhs, Node rhs) { return new DivNode(lhs,rhs); }
     @Override Node copyF() { return new DivFNode(null,null); }
diff --git a/chapter13/src/main/java/com/seaofnodes/simple/node/SubNode.java b/chapter13/src/main/java/com/seaofnodes/simple/node/SubNode.java
index 33b6a162..0f2deb33 100644
--- a/chapter13/src/main/java/com/seaofnodes/simple/node/SubNode.java
+++ b/chapter13/src/main/java/com/seaofnodes/simple/node/SubNode.java
@@ -27,14 +27,15 @@ public class SubNode extends Node {
             if (i0.isConstant() && i1.isConstant())
                 return TypeInteger.constant(i0.value()-i1.value());
         }
+        // Sub of same is 0
+        if( in(1)==in(2) )
+            return TypeInteger.ZERO;
+
         return in(1)._type.meet(in(2)._type);
     }
 
     @Override
     public Node idealize() {
-        // Sub of same is 0
-        if( in(1)==in(2) )
-            return Parser.ZERO;
 
         // x - (-y) is x+y
         if( in(2) instanceof MinusNode minus )