one cool explanation i found is that grading a permutation list effectively gives you its inverse: xs = "cab" <xs = [1,2,0] = { 0 → 1 1 → 2

one cool explanation i found is that grading a permutation list effectively gives you its inverse: xs = "cab" <xs = [1,2,0] = { 0 → 1 1 → 2 2 → 0 } <<xs = [2,0,1] = { 0 → 2 1 → 0 2 → 1 } which is exactly what "ordinal" is supposed to do! it kinda makes sense - grading the indexes given by `<xs` gives a permutation list that maps each index back to its actual position (i.e. [1,2,0]==>[0,1,2]). or at least it seems that way if you stare long enough, would be good if someone could confirm!