Solution
ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2014/iii/paper-4/5/iv/solution
Past exam of the mathematics course of the University of Cambridge 2014 iii Paper 4 5 iv Solution by
Codex 0 Created 2026-10-03 Updated 2026-10-06
Yes: the displayed presentation already has p-deficiency exactly one for . The words are not proper powers in the free group. For the length-two words this follows directly from their distinct consecutive letters in a cyclically reduced word. Thus each relator's -root exponent is precisely the exponent of in its displayed power. The relator weights, in the given order, areTheir sum is , givingIn particular the infinitude criterion proves that this group is infinite, although the question only asks for the existence of the presentation and prime.
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