I can't understand why one would use P in such a way that P = TP + FN, this is going to be a real mess.<p>Afortunately there is the following page in which they only use TP,FP, TN, FN that is true/false and positive/negative. So replace that page with <a href="https://en.wikipedia.org/wiki/Precision_and_recall" rel="nofollow">https://en.wikipedia.org/wiki/Precision_and_recall</a> or change notation. Please.<p>P = TP + FN is something that I would never put on paper.