R (complexity)

In computational complexity theory, R is the class of decision problems solvable by a Turing machine, which is the set of all recursive languages. R is often identified with the class of 'effectively computable' functions (the Church-Turing thesis).

Since we can decide any problem for which there exists a recogniser and also a co-recogniser, the class is equal to $RE \cap coRE$ .

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Important complexity classes (more)
P • NP • co-NP • NP-C • co-NP-C • NP-hard • UP • #P • #P-C • L • NL • NC • P-C • PSPACE • PSPACE-C • EXPTIME • EXPSPACE • PR • RE • Co-RE • RE-C • Co-RE-C • R • BQP • BPP • RP • ZPP • PCP • IP • PH