// Correctness for the case where the master pays
// (final parity of number of number of "agrees"s matches that of N)
(pay=0) => P>=1 [ F "done" & parity=func(mod, N, 2) ]
// Correctness for the case where a cryptographer pays
// (final parity of number of number of "agrees"s does not match that of N)
(pay>0) => P>=1 [ F "done" & parity!=func(mod, N, 2) ]