Post  Correspondence problem(PCP 1946) is another undecidable problem like Turing Halting problem.
Channel: Somenath Roy Choudhury
Date: 2022-04-21

The Post correspondence problem is an undecidable decision problem that was introduced by Emil Post in 1946. 

Because it is simpler than the halting problem and the Entscheidungsproblem it is often used in proofs of undecidability..