fact: Definition queens_state_nondeter n : M (seq Z) := do s <- get ; do rs <- perms (map Z_of_nat (iota 0 n)); put empty >> (do ok <- safe2 (place n rs) ; (put s >> guard ok)) >> Ret rs.
imports: ZArith mathcomp(all_ssreflect) infotheo(ssrZ) monae_lib hierarchy monad_lib fail_lib state_lib