theorem Th59: :: MUSIC_S1:74

for MS being non empty satisfying_Real satisfying_equiv satisfying_interval satisfying_commutativity satisfying_Nat satisfying_harmonic_closed satisfying_fifth_constructible classical_fifth satisfying_octave_constructible classical_octave satisfying_octave_descendent_constructible MusicStruct
for fondamentale being Element of MS holds (spiral_of_fifths (MS,fondamentale,fondamentale)) . 2 = (9 / 8) * (@ fondamentale)