Example: Scalar accounting is insufficient

Deleting a crossing token $\{A,B\}$ and an internal token $\{B,B^{\prime }\}$, then creating edges $B\to A$ and $B^{\prime }\to A$, preserves the scalar count of links. It increases the number of crossing links from one to two. The grammar excludes the second edge because no consumed token had endpoints $\{B^{\prime },A\}$.