He probably did not talk about it because this post was an announcement of his paper: https://arxiv.org/abs/1912.08258 https://arxiv.org/abs/1912.08258, the XOR

He probably did not talk about it because this post was an announcement of his paper: https://arxiv.org/abs/1912.08258 https://arxiv.org/abs/1912.08258, the XOR filter description starts at page 3.