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 * this work for additional information regarding copyright ownership.
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 * (the "License"); you may not use this file except in compliance with
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 *
 *     http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.lucene.search.similarities;


import org.apache.lucene.search.Explanation;

The lambda (λw) parameter in information-based
models.
See Also:
IBSimilarity
@lucene.experimental
/**
 * The <em>lambda (&lambda;<sub>w</sub>)</em> parameter in information-based
 * models.
 * @see IBSimilarity
 * @lucene.experimental
 */
public abstract class Lambda {
  
  
Sole constructor. (For invocation by subclass 
constructors, typically implicit.)
/**
   * Sole constructor. (For invocation by subclass 
   * constructors, typically implicit.)
   */
  public Lambda() {}

  
Computes the lambda parameter. /** Computes the lambda parameter. */
  public abstract float lambda(BasicStats stats);
  
Explains the lambda parameter. /** Explains the lambda parameter. */
  public abstract Explanation explain(BasicStats stats);
  
  
Subclasses must override this method to return the code of the lambda
formula. Since the original paper is not very clear on this matter, and
also uses the DFR naming scheme incorrectly, the codes here were chosen
arbitrarily.
/**
   * Subclasses must override this method to return the code of the lambda
   * formula. Since the original paper is not very clear on this matter, and
   * also uses the DFR naming scheme incorrectly, the codes here were chosen
   * arbitrarily.
   */
  @Override
  public abstract String toString();
}