Let $L/K$ be a field extension, $G$ an abelian group and let $\rho_1,\rho_2$ be two irreducible representations of $G$ defined over $L$. When is the direct sum $\rho_1\oplus \rho_2$ defined over $K$?
2026-03-25 16:03:48.1774454628
Field of Definition of a Direct Sum of Representations
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