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In mathematics, a cubic form is a homogeneous polynomial of degree 3, and a cubic hypersurface is the zero set of a cubic form. In , Boris Delone and Dmitriĭ Faddeev showed that binary cubic forms with integer coefficients can be used to parametrize orders in cubic fields. Their work was generalized in to include all cubic rings,〔A cubic ring is a ring that is isomorphic to Z3 as a Z-module.〕〔In fact, Pierre Deligne pointed out that the correspondence works over an arbitrary scheme.〕 giving a discriminant-preserving bijection between orbits of a GL(2, Z)-action on the space of integral binary cubic forms and cubic rings up to isomorphism. The classification of real cubic forms is linked to the classification of umbilical points of surfaces. The equivalence classes of such cubics form a three-dimensional real projective space and the subset of parabolic forms define a surface – the umbilic torus or umbilic bracelet. ==Examples== *Elliptic curve *Fermat cubic *Cubic 3-fold *Koras–Russell cubic threefold *Klein cubic threefold *Segre cubic 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Cubic form」の詳細全文を読む スポンサード リンク
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