... node, the t and b statements, with the t statement written above the b statement. Let us say that troo~,broot and tloot= bLoo~ are the t and b statements of the root and foot nodes of the auxiliary ... foot of the auxiliary tree. Thus, on adjoining, we unify t, with troot, and b, with b/oot. In fact, this adjoining-is permissible only if t.oo~ and t. are compatible and so are b/oot and ... will now define the operation of adjoining. Consider the adjoining of/ ~ at the node marked with * in a. The subtree of a under the node marked with * is excised, and/ 3 is inserted in its place....