Sum of two squares in biquadratic fields
Wenhuan Huang
Abstract
This paper gives an algorithm to determine whether a number in a biquadratic field is a sum of two squares, based on local-global principle of isotropy of quadratic forms.
Wenhuan Huang
This paper gives an algorithm to determine whether a number in a biquadratic field is a sum of two squares, based on local-global principle of isotropy of quadratic forms.
This paper contains 5 sections, 7 theorems, 31 equations.
Lemma 1
Let $\mathbb{Q}_2(\sqrt{k})$ be a quadratic extension on $\mathbb{Q}_2$, $k\in\{2,3,7,10,11,14,5\}$, then $t\in \mathbb{Q}_2(\sqrt{k})$ is a square, if and only if ($k=2$)$t=2^mr$, $m\geq0$ an integer, $\sqrt{2}\nmid r$, $r\equiv 1, 3+2\sqrt{2}\pmod{4\sqrt{2}}$. ($k=3$)$t=(\sqrt{3}-1)^{2m}r$, $m\geq