Solution
ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2026/iii/paper-128/1/b/i/solution
Choose a successor ordinal , and then choose a limit ordinal . The level satisfies the condensation sentence for the constructible hierarchy. The level cannot satisfy it: otherwise condensation would give for a limit , butwould imply the impossible equality . Thus the condensation sentence belongs to but not to , and .
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