Logarithms of cycle period versus logarithms of rotation period for the sample stars. Here, the two branches are labelled with different signs and the different B − V ranges are colour-coded. Furthermore, the dashed lines are depicted the estimated trends in the range 0.5 ≤ B − V ≤ 1.1 of the cycle-rotation relations in both branches and the dotted line represents the trend with a fixed slope 1 for the short-cycle branch.