16 Our novel weights fall in a novel 14 Formal derivation of (1): xi, yi | π)P (π); now observe that P (xi, yi | π) = 1 or 0 according to whether π ∈ Π.
15 : (K, ⊗) is a monoid (i.e., ⊗ : K × K → K is associative) with identity 1.