标题： 与爱因斯坦时空相关的椭圆纤维化 显示英文标题

标题： Elliptic fibrations associated with the Einstein spacetimes

摘要： 给定一个共形非平坦的爱因斯坦时空，我们定义在其上的一个纤维丛$P$。 该纤维丛的纤维是椭圆曲线（二维环面）或其退化形式。 它们的拓扑结构取决于爱因斯坦度量的Weyl张量的代数类型。 纤维丛$P$是时空上零方向丛的二重分支覆盖，并配备有六个线性无关的1-形式，这些1-形式满足某些相对简单的方程组。 显示英文摘要

摘要： Given a conformally nonflat Einstein spacetime we define a fibration $P$ over it. The fibres of this fibration are elliptic curves (2-dimensional tori) or their degenerate counterparts. Their topology depends on the algebraic type of the Weyl tensor of the Einstein metric. The fibration $P$ is a double branched cover of the bundle of null direction over the spacetime and is equipped with six linearly independent 1-forms which satisfy certain relatively simple system of equations.