Here is the syntax tree for the expression $((x+y)-((x+y)**(x-y)))+((x+y)**(x-y))$ :

The letters A$,$ B$,...,$ I are used to name the nodes, and are not part of the expression tree. The operator labels of the interior nodes are the,,$+-$ or $*$ adjacent to the nodes.

Assuming we do not use any algebraic laws $($e$.$g$.,$ commutativity$)$ to transform the tree, which pairs of nodes will be combined when we construct an expression DAG from this tree? What does DAG stand for? Draw the resulting DAG.