As in example (66b), an inferred relation is triggered between the interpretations of T2 and T1, namely, explanation(interp(T2),interp(T1)).
then, as a result of β:for ex1 adjoining at t2 and β:for ex2 adjoining at the root of the higher (66c) and (66d) differ only in the derivation of the interpretation that for example then abstracts over.