Ladner's theorem

Theorem ("NP intermediate" languages, [Lad75])

Suppose P≠NP. Then there exists a language $L \in$ NP $\setminus$ P that is not NP-complete (i.e. "NP-intermediate" language)

References

1. S. Arora, B. Barak. Computational Complexity: A Modern Approach, Cambridge University Press, 2009, pp. 61-72.
2. R. E. Ladner, “On the Structure of Polynomial Time Reducibility,” J. ACM, vol. 22, no. 1, pp. 155–171, Jan. 1975, doi: 10.1145/321864.321877.
3. https://en.wikipedia.org/wiki/NP-intermediate
4. https://www.cs.ucdavis.edu/~rogaway/classes/220/winter06/ladner-theorem.pdf
5. https://www.youtube.com/watch?v=Dfdi2mMbuIs