Figure 2

Reciprocal and non-reciprocal variant edges. Two classes of variant edges in the interval-adjacency graph. Reciprocal variants are pairs of variant edges incident to the same four interval edges (I _p , I_p+1, I _q , I_{q+ 1}), while non-reciprocal variants are the cases where only a single variant edge is incident to the four interval edges defined by the variant edge. A trivial reciprocal variant has equal inferred multiplicities: μ(A) = μ(A'), μ(I _p ) = μ(I_p+1), and μ(I _q ) = μ(I_q+1).