0 votes 0 votes Let $C$ be a language. Prove that $C$ is Turing-recognizable iff a decidable language $D$ exists such that $C = \{x \mid \exists y (\langle{ x, y \rangle} \in D)\}$. Theory of Computation michael-sipser theory-of-computation recursive-and-recursively-enumerable-languages decidability proof + – admin asked Oct 17, 2019 admin 172 views answer comment Share Follow See all 0 reply Please log in or register to add a comment.