Hi. First I'd like to let you know that I'm probably in the wrong section, but this is because I really, honestly, don't know where to put this question. If I knew what the problem is about, I'd have looked up on the Internet before asking.
So, I've made a picture explaining my problem : http://i.imgur.com/EkQZq.png .
If anyone can explain me how to solve this kind of problem and tell me what domain it is related to, it would be greatly appreciated.