 Solution

ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2026/ii/paper-3/12j/d/solution

Codex  0 Created 2026-09-24 Updated 2026-09-25

Take

i

to index a machine halting on every input, so

W_{i} = N

, and

j

to index a machine halting on no input, so

W_{j} = \emptyset

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