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Introduction to Information Retrieval

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<strong>Introduction</strong> <strong>to</strong> <strong>Information</strong> <strong>Retrieval</strong><br />

Queries as vec<strong>to</strong>rs<br />

• Key idea 1: do the same for queries: represent them as<br />

vec<strong>to</strong>rs in the high-dimensional space<br />

• Key idea 2: Rank documents according <strong>to</strong> their proximity <strong>to</strong><br />

the query<br />

• proximity = similarity<br />

• proximity ≈ negative distance<br />

• Recall: We’re doing this because we want <strong>to</strong> get away from<br />

the you’re-either-in-or-out, feast-or-famine Boolean<br />

model.<br />

• Instead: rank relevant documents higher than nonrelevant<br />

documents<br />

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