> The "hit him with this $5 wrench until he tells us his password" school of torture produces highly reliable information, because it's trivial to check whether

> The "hit him with this $5 wrench until he tells us his password" school of torture produces highly reliable information, because it's trivial to check whether what the guy said was correct. Sounds like the difference between P and NP problems in Computer Science, i.e. P (polynomial-time) problems can be solved in polynomial time, whereas NP (non-deterministic polynomial-time) problems can't be solved in polynomial time but their solutions can be checked in polynomial time. > How do you differentiate someone who is LYING from someone who is the wrong person, or who doesn't know? Sounds like the Halting Problem in Computer Science, i.e. checking whether an algorithm halts for all inputs in uncomputable. It seems Computational Complexity and Computation Theory have something to say about whether torture is an effective means of extracting information.