FA-81064 / Music interval and transposition theory / Member archive

Pitch-class set prime form (right-packed): empty set treated as invalid · case 04

The empty set returns None instead of the empty prime form [].

Member previewVariant 4 · 3 implementations · 8 checks per implementation

Case contract

Input a list of integers. Compute the right-packed normal form of the set and of its inversion (p -> -p mod 12), transpose each to start on 0, and return whichever is more packed: compare the last value, then the penultimate, and so on toward the second (the original wins ties). Empty input returns []; non-integers return None.

Why this case matters

Set-class labelling depends on prime forms being computed identically for every member of a class.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
oracle 7	`null`	`[]`	Failed

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