 Solution

ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2021/ii/paper-4/4f/iii/solution

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

A word containing neither

01

nor

10

cannot change symbol. The language is therefore

0^{*} \cup 1^{*}

, hence is regular.

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