The simplistic invariant in our emotional subconsious is not only creating the simplicial sub-melody by the melody centers, but also the simplicial sub-chord-progression
E.g. when in diatonic scale we play a chord progression involving 1M , 2m, 3m, 4M 5M 6m , we may
realize that the 3 minors 2m , 3m, 6m, are lower relative chords ofthe 4M, 5M, 1M and so we actually may havea salternative well fitting also chord progression one that has only the 3 majors 1M, 4M, 5M. which can of course be called the simplicial sub-chord-progression.
An example is to try to improvise melodically on the next quite long piece of gypsu jazz
https://www.youtube.com/watch?v=wy9LiSeDQiU&t=412s&ab_channel=LewisLuongRelaxationCafe
It becomes after some time easy, because it is as if improvising over a simple chord progression involving only the 1M, 4M, 5M.
