Reverse Turing test section. Since Turing test judges are sometimes presented with genuinely human subjects, as a control, it inevitably occurs that a small proportion of such control subjects are judged to be computers. This is considered humorous and often embarrassing for the subject. This situation may be described literally as the human "failing the Turing test", for a computer (the intended subject of the test) achieving the same result would be described in the same terms as having failed. The same situation may also be described as the human "failing the reverse Turing test" because to consider the human to be a
Turing completeness it is impossible to determine whether this characteristic will hold. This impossibility poses problems when analyzing real-world computer programs. For example, one cannot write a tool that entirely protects programmers from writing infinite loops, or protects users from supplying input that would cause infinite loops. One can instead limit a program to executing only for a fixed period of time (timeout), or limit the power of flow control instructions (for example, providing only loops that iterate over the items of an existing array). However, another theorem shows that there are problems solvable by Turing-complete languages that cannot be solved by