title: How do scoring and indexing work together in Information Retrieval Systems
body: <p>I have a brief understanding of indexing ( inverse indexing ) and scoring ( like tf-idf ) in IR . Generally , if there is no indexing , a tf-idf matrix is pre-calculated , and a corresponding tf-idf vector is made for the query and then scores calculated for each document . </p>
  
  <p>What is this flow like when there is indexing done for the documents , specifically how does a library like apache lucene or terrier process a query to evaluate scores for documents .</p>