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2.1.1 Chord-graph fidelity

Question. Does every chord transition in the harmonic backbone follow a legal motion type — single edge, compound perturbation, window slide, or fiber inversion?

How to check.

  1. List every chord in the harmonic backbone. Identify the orbit of each.
  2. For every adjacent pair: count the common tones. If the common tones equal 3, the transition is a single edge (legal). If 2, it’s a compound perturbation (legal but more complex). If 0-1, the transition needs justification — either a window slide (entire chord transposed) or a fiber inversion (orbit unchanged but inversional state different) or it’s an illegal jump.
  3. Flag any transition that does not fit one of these motion types.

Common findings. Most beginning OTH composers stick to single edges, which is fine. Compound perturbations should be reserved for moments that warrant the extra motion (textural climaxes, structural arrivals).