Alpha recursion theory Arithmetical set Church–Turing thesis Computability logic Computable function Computation Decision problem Effective method Entscheidungsproblem Enumeration Forcing (recursion theory) Halting problem History of the Church–Turing thesis Lambda calculus List of undecidable problems Post correspondence problem Post's theorem Primitive recursive function Recursion (computer science) Recursive language Recursive languages and sets Recursive set Recursively enumerable language Recursively enumerable set Reduction (recursion theory) Turing machine