1. Consider the following fragment of a positional index with the format: word: document: position, position, ...; document: position, ... ... Gates: 1: 3; 2: 6; 3: 2,17; 4: 1 IBM: 4: 3; 7: 14 Microsoft: 1: 1; 2: 1,21; 3: 3; 5: 16,22,51 The /k operator, word1 /k word2 finds occurrences of word1 within k words of word2 (on either side), where k is a positive integer argument. Thus k = 1 demands that word1 be adjacent to word2. a. Describe the set of documents that satisfy the query Gates /2 Microsoft. b. Describe each set of values for k for which the query Gates /k Microsoft returns a different set of documents as the answer.