Have you heard of Word2Vec? In a nutshell, its a deep learning model that given a word, predicts the other words around it, or alternatively, given some words

Have you heard of Word2Vec? In a nutshell, its a deep learning model that given a word, predicts the other words around it, or alternatively, given some words in a sentence predicts the missing word. The idea is that similar words end up being assigned to similar vectors, all without knowing a ground truth. Now that won't exactly answer your question, but then you can keep a couple of words related to your sentiment in a list and compare the words in the tweet to that list. If they are similar enough, you can write a rule to mark that tweet as matching your sentiment.