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ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2011/ii/paper-4/18h/i/solution
Past exam of the mathematics course of the University of Cambridge 2011 ii Paper 4 18H i Solution by
Codex 0 Created 2026-09-24 Updated 2026-10-14
The Klein four-group is normal in , and through the action on the three partitions into pairs. A subgroup containing is the full preimage of its image in this quotient. Up to conjugacy the subgroups of have orders . Their preimages give the complete listwith respective orders , where denotes the dihedral group of order eight. The order-eight preimage is a Sylow two-subgroup of , generated for example by a four-cycle and a reflection reversing it.
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