Direct Acyclic Graph(DAG): Example
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• Parse tree for
   x = a*b + a*b:
S
• DAG for
   x = a*b + a*b:
E
E
E
=
*
i
i
i
x
=
a
*
b
*
i
i
a
*
b
+
+
E
E
E
E
Ex
=
*
+
Ea
Eb
Note: DAG has no redundant nodes.