Answer following with True/False

1.We always do exact same tokenization of document and query words ,generally by processing queries with same tokenizer.

2.Removing stop words will cause problems for phrase searches, for example a relational query. "Flights to London".

3. Stop words are some extremely rare words are excluded from the vocabulary entirely

4. Stop words appear to be of little value in helping select documents matching a user need.

5. Removing stop words significantly reduces the number of postings a system has to store.

6. We may implicitly define equivalence classes of terms by using mapping rules, such as deleting periods or hyphens in a term

7. For choosing stemmers, the exact stemmed forin doesn't matter, only the equivalence classes it forms.

8.Stemming should be invoked at indexing but not while processing query

9.Stemming increases size of vocabulary