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    <title>Measures</title>
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    <h1>Relatedness Measures</h1>

    <h2>Lesk  </h2>
    <p>The Lesk measure works by finding overlaps in the extended definitions 
      of the two concepts. The relatedness score is the sum of the squares of 
      the overlap lengths.  For example, a single word overlap results in a 
      score of 1.  Two single word overlaps results in a score of 2. A two 
      word overlap (i.e., two consecutive words) results in a score of 4. A 
      three word overlap results in a score of 9.    
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    <h2>Vector</h2>
    <p>The vector measure works by forming second-order 
      co-occurrence vectors from the UMLS extended definitions of concepts. 
      The relatedness of two concepts is determined as the cosine of the 
      angle between their vectors. 
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