Q:  in the key of C the V chord is G. by the powers of negative harmony G7 becomes Fm6.. so its a minor plagal cadence. i get that and i use it often because i really like the sound of it. here is where i get confused though: how does Fm6 actually derive from G7? and would (if the same techniques applied) every other chord from the keycenter also have a 'negative' version??