Computably enumerable set

A **computably enumerable (c.e.) set**, also known as a recursively enumerable set, is a fundamental concept in computability theory and mathematical logic. A set \( S \) of natural numbers is considered computably enumerable if there is a Turing machine that can enumerate the elements of \( S \). This means that: 1. There exists a Turing machine which, when run, will output the members of \( S \) one by one, possibly with repetitions.