Recursive set
In recursion theory (otherwise called the theory of computability) a set S of integers, or natural numbers, or literal strings, or tuples of any of the above, is recursive or Computable or Decidable if there is an algorithm that, when given a number or literal string or tuple (as the case may be) returns a correct yes-or-no answer to the question of whether the input number, string, or tuple is a member of the set S.
See also