Is the input text lower cased before processing to the tensorflow embeding classification pipeline? I hope there will be no difference when write in upper cases like at beginning of sentence. So that words like the and The are the same?
Look here what Tomas Mikolov ( one of the developers of Word2Vec - a popular word embedding method) says.
There is no universal answer. It all depends on what you plan to use the vectors for. In my experience, it is usually good to disconnect (or remove) punctuation from words, and sometimes also convert all characters to lowercase. One can also replace all numbers (possibly greater than some constant) with some single token such as <NUM> .
All these pre-processing steps aim to reduce the vocabulary size without removing any important content (which in some cases may not be true when you lowercase certain words, ie. ‘Bush’ is different than ‘bush’, while ‘Another’ has usually the same sense as ‘another’). The smaller the vocabulary is, the lower is the memory complexity, and the more robustly are the parameters for the words estimated. You also have to pre-process the test data in the same way.
By default they’re lowercased: https://github.com/RasaHQ/rasa_nlu/blob/master/rasa_nlu/featurizers/count_vectors_featurizer.py#L67