Proposition: Exact guard versus report

A zero rounded length is not an exact incidence test. For a born edge of length $cs$, $c>0$, its floor report is zero for every $0<s<2^{-p_{\mathrm{r}}}/c$. The event guard must use exact $j=0$, mode, and permission.

Proof. In that interval $0<2^{p_{\mathrm{r}}}cs<1$. Its floor is zero although the edge is active and positive.