Determine the number of effectively computable methods
Determine how many effectively computable methods exist in total under the notion of effective computability associated with the Church–Turing thesis, or otherwise characterize the size of this set.
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As we discussed in Section 2.1, the Church-Turing thesis postulates that all "effectively computable" methods can be computed by a Turing Machine. However, the definition of what constitutes an "effectively computable" method is not well-defined. Moreover, we currently do not know how many such methods exist in total.
— On the Computability of Artificial General Intelligence
(2512.05212 - Mappouras et al., 4 Dec 2025) in Section 4.2 (Limitations)