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A Klumpenhouwer Network, named after its inventor, Canadian music theorist and former doctoral student of David Lewin's at Harvard, Henry Klumpenhouwer, is "any network that uses T and/or I operations to interpret interrelations among pcs". According to George Perle, "a Klumpenhouwer network is a chord analyzed in terms of its dyadic sums and differences," and "this kind of analysis of triadic combinations was implicit in," his "concept of the cyclic set from the beginning", cyclic sets being those "sets whose alternate elements unfold complementary cycles of a single interval."
"Klumpenhouwer's idea, both simple and profound in its implications, is to allow inversional, as well as transpositional, relations into networks like those of Figure 1," showing an arrow down from B to F♯ labeled T7, down from F♯ to A labeled T3, and back up from A to B, labeled T10 which allows it to be represented by Figure 2a, for example, labeled I5, I3, and T2. In Figure 4 this is I7, I5, T2 and I5, I3, T2.
Lewin asserts the "recursive potential of K-network analysis"... "'in great generality: When a system modulates by an operation A, the transformation f' = A f A -inverse plays the structural role in the modulated system that f played in the original system."
Given any network of pitch classes, and given any pc operation A, a second network may be derived from the first, and the relationship thereby derived 'network isomorphism' "arises between networks using analogous configurations of nodes and arrows to interpret pcsets that are of the same set class – 'isomorphism of graphs'. Two graphs are isomorphic when they share the same structure of nodes-and-arrows, and when also the operations labeling corresponding arrows correspond under a particular sort of mapping f among T/I."