广义Ehlers恒等式和Raychaudhuri方程的统一几何基础
Unified geometrical basis for the generalized Ehlers identities and Raychaudhuri equations
摘要：
它表明，类时，类空和零版本的埃勒斯身份，以及随后的Raychaudhuri方程，可能都是在一个单一的几何方法的基础上的定义的黎曼曲率张量指定相对于相应的同余。尽管如此，类空和空的情况有许多值得特别注意的重要特性。
英文摘要：
It is shown that the timelike, spacelike and null versions of the Ehlers identity, as well as ensuing Raychaudhuri equations, might be all derived within a single geometrical approach based on the definition of the Riemann curvature tensor specified with respect to the corresponding congruence. Still, spacelike and null cases have a number of non-trivial peculiarities deserving special attention.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
