Turing test with a human, both questioned in parallel by an interrogator. Since the Turing test is a test of indistinguishability in performance capacity, the verbal version generalises naturally to all of human performance capacity, verbal as well as nonverbal (robotic). Turing's original article describes a simple party game involving three players. Player A is a man, player B is a woman and player C (who plays the role of the interrogator) is of either sex. In the imitation game, player C is unable to see either player A or player B, and can communicate with them only through written notes. By
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