input: Background: It was shown by Ladner that if P ≠ NP then there exist problems in NP that are neither in P nor NP-complete. Such problems are called NP-intermediate problems. The graph isomorphism problem, the discrete logarithm problem and the integer factorization problem are examples of problems believed to be NP-intermediate. They are some of the very few NP problems not known to be in P or to be NP-complete.
  Question: Who demonstrated that P= NP implies problems not present in P or NP-complete?
  Answer:<extra_id_0>.
output: <extra_id_0> Ladner<extra_id_1>