In the context of natural language processing, can anyone give a concrete example of True Positive, True Negative, False Positive, False Negative?
Imagine a hot news classifier.

True Positive (TP): 
Reality: a piece of hot news. 
classifier predicts: hot.

True Negative (TN): 
Reality: not a piece of hot news. 
classifier predicts: not hot.

False Positive (FP): 
Reality: not a piece of hot news.
classifier predicts: hot.

False Negative (FN): 
Reality: a piece of hot news. 
classifier predicts: not hot.