Here is the theorem cited in [Serguei Popov's answer](https://mathoverflow.net/a/272893/6094): <hr /> [![Thm352][1]][1] <hr /> and here are the three assumptions: <hr /> [![L012][2]][2] <hr /> [1]: https://i.sstatic.net/4jxRN.jpg [2]: https://i.sstatic.net/Tt8nQ.jpg