exchange A technique of prolongation
in which tones in a given arrangement of voices are later replicated
in a different arrangement (inversion). Typically, a third is inverted
to become a sixth in the outer parts.
In the example, taken from Variation 11, the augmented fourth and
its resolution to a sixth in m. 5 are replicated as a diminished
fifth resolving to a third in m. 7. This repetition provides for
the Urlinie notes in the obligatory
register. It is important to note that the inverted repetition
does not necessarily imply a repetition of structural importance.
Schenker show by the graph that both dissonance and resolution groups
stand for a single V-I
progression supporting the upper voice 4-3.