Exact guards and actual particle support

For an edge of length $cs$, floor quantization with step $2^{-b}$ reports zero on $0\le s<2^{-b}/c$, not only at $s=0$. A zero report is therefore not the exact incidence guard.

Adding a remote particle label to the support of a vacuum exchange also does not make the particle incident to the changed cells. The present example changes the actual particle link.

Finally, an occupancy guard is not the geometry-only guard of A:cor:G-event. It changes the observation boundary and cannot be called the same rule.