12.07.2015 Views

Dictionaries and Tolerant Retrieval

Dictionaries and Tolerant Retrieval

Dictionaries and Tolerant Retrieval

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Introduction to Information <strong>Retrieval</strong>Sec. 3.1Hashes• Each vocabulary term is hashed to an integer• (We assume you’ve seen hashtables before)• Pros:• Lookup is faster than for a tree: O(1)• Cons:• No easy way to find minor variants:• judgment/judgement• No prefix search [tolerant retrieval]• If vocabulary keeps growing, need to occasionally do theexpensive operation of rehashing everything7

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