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There is a well known bijection between the discriminant of quadratic extensions of $\mathbb Q$ and the fundamental discriminant of binary quadratic forms $ax^2 + bxy + cy^2, a,b,c\in \mathbb Q$.

Is there a similar relation between the relative discriminant of quadratic extensions of number fields, say $E/F$ over $\mathbb Q$, and discriminants of binary quadratic forms $ax^2 + bxy + cy^2, a,b,c\in F$?

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1 Answer 1

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Relative discriminants of quadratic extensions of a number field $F$ are ideals, which need not be principal. Discriminants of quadratic forms are elements of $F$ by definition.

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