In computational complexity theory, R is the class of decision problems solvable by a Turing machine, which is the set of all recursive languages.
Contents
Equivalent formulations
R is equal to the set of all total computable functions.
Relationship with other classes
Since we can decide any problem for which there exists a recogniser and also a co-recogniser by simply interleaving them until one obtains a result, the class is equal to RE ∩ coRE.
References
R (complexity) Wikipedia(Text) CC BY-SA