https://vegetablefj.github.io/blog/categories/%E7%A2%8E%E7%A2%8E%E5%BF%B5/Recent content in 碎碎念 on vegetablefjHugoen-usvegetablefjSat, 18 Apr 2026 04:38:59 +0800https://vegetablefj.github.io/blog/post/2026/04/18/%E7%A2%8E%E7%A2%8E%E5%BF%B5/Sat, 18 Apr 2026 04:38:59 +0800https://vegetablefj.github.io/blog/post/2026/04/18/%E7%A2%8E%E7%A2%8E%E5%BF%B5/碎碎念 M9 你说的对，但是$M_9$是一个72阶群，symplectic automorphism group的smooth cubic fourfold的方程总是可以写成 $$x_1^3+x_2^3+x_3^3-3(1-\sqrt{3})x_1x_2x_3+(\omega+\sqrt{-1}\omega^2)(y_1^3+y_2^3+y_3^3-3(1+\sqrt{3})y_1y_2y_3)$$ 和 $$(\sqrt{-1}-\omega^2)(x_1y_1^2+x_2y_2^2+x_3y_3^2-(1-\sqrt{3})(x_1y_2y_3+y_1x_2y_3+y_1y_2x_3)) +x_1^2y_1+x_2^2y_2+x_3^2y_3-(1+\sqrt{3})(y_1x_2x_3+x_1y_2x_3+x_1x_2y_3)$$ 的