Originally Posted by Zegie
As a purely theoretical exercise and in a crazy moment I started to consider the notes in a 12 bar in G just to see what 'overlaps' there might be. I noted that the fifth of G is the D and the fifth of C Is the G and of course the first of D is D. So it could be argued that all you need are the notes G and D to play a 12 bar.
It would be the most unexciting bass line ever played but it made me begin to wonder what other 'lite' versions for chord progressions might worth exploring.
Not only could be but is.
Many Chord progression overlap..that is the beauty of a progressions that it flows.
Your example is simple Cycle of 5ths based on Tetra chords
C is CDEF GABC
G is GABC DEFG
D is DEFG ABCD
to make them the correct keys you add a # to the F for G major, F & C for D Major. This also allows you to 'overlap' in to A minor, E minor and Bb minor.
Check out a "50s" progression of I VI IV V or I VI II V same idea again of the Harmonised Major scale.