We can map t to this graph by applying the following linear tree homomorphism h into H 2 : A derivation of the form * 0 (t 1 , t 2 ) evaluates to the same graph as t 1 ; the graph value of t 2 is ignored.
if we assume that the subtree of t for cdd evaluates to some arbitrary graph G 0 , the complete derivation t evaluates to G 1 .