test23.frm

signature { automatic } theory
{
<>(n1 & <>(n2 & <>(n3 & <>(n4 & <>(n5 & <>(n6))))));
(n1:!n2 & n2:!n3 & n3:!n4 & n4:!n5 & n5:!n6 & n6:!n1);
[](p1 -> [](p2 -> [](p3 -> [](p4 -> [](p5 -> [](p6)))))) 
}