It's not normal to be loopless:Every normal box has a loop. Proof: In view of {$T$} is Loopless iff {$\Delta T$} is Loopless, it is sufficient to show that every strictly triangular box has a loop. Let {$a\times b\times c$} be strictly triangular with {$a\le b<c\le a+b$}. Then for any {$r<a+b-c$}, the following is a loop:  |