I don't agree that they're redefining even vs. odd. It's more like positive sloping vs. negative sloping. The reason they've introduced the y variable instead o

I don't agree that they're redefining even vs. odd. It's more like positive sloping vs. negative sloping. The reason they've introduced the y variable instead of referring to the slope of those lines is that they're going to use the y value as a class label later. I agree that the paper is written in dense technical language, but the point is that the authors are writing for other academics, not laypeople. They could go to some lengths to avoid using symbols like ~, but those symbols are completely standard in stats and ML. If you haven't seen them, there's a good chance you don't have the right background to follow their paper anyway. All writing styles have their place. In textbooks and blog posts, it's completely sensible to have an index of notation, and to use natural language to express ideas. But when writing for an audience of trained scientists, it's a different matter.