I'm trying to compile BPI.tex here because, as you can see, the given compiled file has the lower end of each page cut off. The problem is: I get lots of "undefined control sequence" errors but if I cut the paragraph containing the error, delete aux and log files, quit TexShop and then recompile, I get the same error on the same line even if the line is then blank (since I cut it out).
What is going on here? Is TexShop broken? Why does editing the file not have any effect? And how can I compile this file?