Johann Sebastian Bach · 1747 · Pitched Music
Core Mechanism
. The Crab Canon without retrograde inversion isn't a different piece; it's no piece. La Disparition with 'e' restored isn't a variant; it's structurally meaningless because word choices were forced by absence, not selected for meaning.
Kernel Engagement
Works within the kernel’s native ground; the structural gap is present but never encountered.
Evidence
The retrograde inversion constraint operates entirely within fifth-based tonal relationships—every pitch decision must satisfy both forward and backward reading while maintaining functional harmony and cadential resolution at the temporal pivot.
Territory
The work operates entirely within fifth-based harmonic organization with functional harmony, cadential resolution, and traditional voice-leading—the palindromic constraint doesn't alter the tonal language but demonstrates its bidirectional structural properties.
Constitutive depth
The work is constituted by the fifth (remove fifth-based relationships and it ceases to be tonal music) but the retrograde constraint is Bach's compositional choice, not an endogenous property generated by the kernel itself—any well-constructed theme could theoretically support similar palindromic treatment.
Legibility
The mechanism is structurally visible to any musically literate listener—the palindromic structure, the convergence at measure 9, and the bidirectional reading are perceptible as foregrounded compositional content, not hidden infrastructure.