A noncoincident cancellation

The incidence occurs in $B_6$: one metric slot at $u$ and the observation scalar slot at $x$ are contracted with the metric and one scalar slot of the vertex at $y$. The remaining fields are a metric at $u$ and a scalar at $y$. The incoming differentiated retarded line and the two differentiated cross-lines have precisely the triangle structure of (eq:triangle).

For example, the local density coefficient ${a_2}^{00}$ contains a nonzero $({\gamma }_{00}{)}^2$ monomial. Temporal derivative components have nonzero conormal symbols on the displayed null direction. This locates the sufficient-criterion issue in the actual incidence inventory, not in an unrelated graph. It does not establish absence of cancellations after summing all tensor components and all eleven branches.