FA-81329 / Music interval and transposition theory / Member archive
Triad and seventh inversion figures: doubled triad labelled as a seventh chord · case 04
A four-note triad with a doubled root (C E G C) is labelled with seventh figures ("7") instead of root position.
Case contract
Input 3 or 4 MIDI integers in any order. The pitch-class set must match a template relative to some root (triads 047 037 036 048; sevenths 047t 037t 047e 036t 0369, t=10 e=11); roots are tried in ascending pitch-class order. The bass is the lowest MIDI note. Return [root_pc, figure] with figures "", "6", "64" for triads and "7", "65", "43", "42" for sevenths by the bass position in the template; otherwise None.
Why this case matters
Figured-bass realisation and harmonic analysis depend on identifying chord root and inversion.
One recorded failure
Sample boundary fixtureThis sample comes from the broken implementation of a controlled reproducer.
| Boundary fixture | Actual | Expected | Outcome |
|---|---|---|---|
| oracle 0 | [0, "7"] | [0, ""] | Failed |
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