Glossary
Permutation Equivalence
Glossary
Set Theory
Permutation equivalence treats musical objects the same if they have the same note names or pitch classes even if the notes come in a different order.
In OC-equivalence, permutation or order still matters, especially which note is on the bottom (the root). In OPC-equivalence, the notes are treated as an unordered collection. A simple example of permutation-equivalent objects are the inversions of the C major triad—in this case we would not care which note is on the bottom, just which notes are present (not their order): C, E, and G.
See Equivalence Groups for a tutorial that runs through some examples.
Set Theory
Permutation equivalence treats musical objects the same if they have the same note names or pitch classes even if the notes come in a different order.
In OC-equivalence, permutation or order still matters, especially which note is on the bottom (the root). In OPC-equivalence, the notes are treated as an unordered collection. A simple example of permutation-equivalent objects are the inversions of the C major triad—in this case we would not care which note is on the bottom, just which notes are present (not their order): C, E, and G.
See Equivalence Groups for a tutorial that runs through some examples.