Post correspondence problem

Not to be confused with the other Post's problem on the existence of incomparable r.e. Turing degrees.
Not to be confused with PCP theorem.

The Post correspondence problem is an undecidable decision problem that was introduced by Emil Post in 1946.[1] Because it is simpler than the halting problem and the Entscheidungsproblem it is often used in proofs of undecidability.

  1. ^ E. L. Post (1946). "A variant of a recursively unsolvable problem" (PDF). Bull. Amer. Math. Soc. 52 (4): 264–269. doi:10.1090/s0002-9904-1946-08555-9. S2CID 122948861.