5. 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 kis 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.