Group is a union of proper subgroups iff. it is non-cyclic

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SUMMARY

A finite group G is a union of proper subgroups if and only if it is non-cyclic. This conclusion is derived from the fact that if G is a union of proper subgroups, then no single subgroup can encompass all elements of G, confirming that G cannot be cyclic. Conversely, if G is non-cyclic, it can be expressed as the union of all its proper subgroups, as no element can generate the entire group.

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Homework Statement



Prove that a finite group is the union of proper subgroups if and only if the group is not cyclic.

Homework Equations



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The Attempt at a Solution


[/B]
" => "
If the group, call it G, is a union of proper subgroups, then, for every subgroup, there is at least one element of G that is not in that particular subgroup. But then we know that none of the subgroups can represent all the elements of G. Therefore, G is not cyclic.

" <= "
If the group is not cyclic, then no element a in G generates G. That means that G is the union of all the <a> subgroups for all a in G.

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