Editing Interactive proof system (section)

=== IP ===
{{main|IP (complexity)}}
Private coins may not be helpful, but more rounds of interaction are helpful. If we allow the probabilistic verifier machine and the all-powerful prover to interact for a polynomial number of rounds, we get the class of problems called '''IP'''.
In 1992, [[Adi Shamir]] revealed in one of the central results of complexity theory that '''IP''' equals '''[[PSPACE]]''', the class of problems solvable by an ordinary [[deterministic Turing machine]] in polynomial space.<ref>Adi Shamir. [http://portal.acm.org/citation.cfm?doid=146585.146609 IP = PSPACE]. ''Journal of the ACM'', volume 39, issue 4, p.869–877. October 1992.</ref>