 Solution

ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2026/ii/paper-4/16j/e/solution

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

x

is hereditarily countable, its transitive closure contains only countably many ranks. Their supremum is a countable ordinal below

ω_{1}

, so

x \in V_{ω_{1}}

 New to topics? Read the docs here!