Yet another proof of Hawking and Ellis's Lemma 8.5.5
arXiv:1407.0340 · doi:10.1088/0264-9381/31/22/227001
Abstract
The fact that the null generators of a future Cauchy horizon are past complete was proved first by Hawking and Ellis [1]. Then Budzyński, Kondracki, and Królak outlined a proof free from an error found in the original one [2]. Finally, a week ago Minguzzi published his version of proof [3] patching a previously unnoticed hole in the preceding two. I am not aware of any flaws in that last proof, but it is quite difficult. In this note I present a simpler one.
A few misleading typos are corrected