Example 1c. Frédéric Chopin, Mazurka in C major, op. 24, no. 2, measures 21–28, segmentation wrought by a combination of GPRs 6 and 1

GPR 6 addresses parallelism, suggesting the downbeats of measures 21 and 25 are both beginnings.
GRP 1 retrospectively associates the F⁵ at the end of measure 24 with the previous material to avoid a one-note group