@egreg I will consider makros. But even if I wouldn't, this should only give me an inpression which symbols are rarely used at all. For example, \bat or \Mundus are such candidates. (Today I've talked to my advisor and we wondered if \up[greekletter] is used. If it's not used, I don't need training data for that)
@DavidCarlisle I don't have experience with parsing PDF files at all. The last time I tried to work with PDFs it was really ugly as no good tools / for parsing / pdf generation existed. So if it's possible, I'd like to avoid that.
@egreg: I had a 23" monitor in my old lab PC, with Slackware. It was a Full HD screen all black with a little blinking white cursor. :) People got so mad at me because of that. I only went X twice a day. :)
@Mario: You have two sides, one out in the field and one in. Each man that's in the side that's in goes out, and when he's out he comes in and the next man goes in until he's out. When they are all out, the side that's out comes in and the side thats been in goes out and tries to get those coming in, out. Sometimes you get men still in and not out.
When a man goes out to go in, the men who are out try to get him out, and when he is out he goes in and the next man in goes out and goes in. There are two men called umpires who stay all out all the time and they decide when the men who are in are out. When both sides have been in and all the men have been out, and both sides have been out twice after all the men have been in, including those who are not out, that is the end of the game.
@FaheemMitha No, both return a number, either 1 or 0; if both are false, both return 0, so TeX compares 00 with 0; otherwise it compare 11, 10 or 01 with 0.
@FaheemMitha Note the missing spaces between 1 and \else and between 0 and \fi.
@FaheemMitha When TeX looks for a <number> it expands token as it goes; whenever it finds a digit it appends it to the candidate digit string and stops when it finds a token that is unexpandable and not a digit.