[L] Leading-tone exchange
A parallel transformation converts a major triad to the minor and vice versa bymoving the third by half-step. In other words C Major is transformed to C Minor just asC Minor is transformed to C Major.
A relative transformation converts a major triad to aminor triad by moving the fifth a whole-step up and vice versa, moves a minor triad to a major triad by moving the root down by whole-step (i.e. C Major to A Minor or A Minorto C Major).
The leading-tone exchange transformation converts a major triad to a minor triad by moving the root down by half-step, and vice versa, from minor to majorby moving the fifth up a half-step to become the root of the resulting triad (i.e. C Majorto E Minor and E Minor to C Major).
《Essential Neo-Riemannian eory for Today’s Musician》——Laura Felicity Mason