But there are many basic difficulties here. One lies in identifying precisely what percepts might be appropriate testing grounds for the evaluation. However valid that assumption may or may not be, the two problems mentioned above remain even for functions more securely grounded in that area. Given competing clusters of the 29 chords under the proposed function, our hope would be to select only good clusters by listening to the piano ostinato. The problem is in determining how far mitigating factors are operative, and how far they should be taken into account, when judging similarity-based boundaries according to perception.
Similarity presupposes a context.
The context of REL is a particular intellectual apparatus. Professor Parncutt's proposed similarity measure is a particular experimental setting. Those relationships have been much maligned in the subsequent similarity literature. I think a more sympathetic re-evaluation, especially of Forte's analytical applications, could prove very illuminating. Richard Hermann's response reached me only as I finished writing this.