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package scala.math

/** 
 *    A trait for representing equivalence relations.  It is important to 
 *    distinguish between a type that can be compared for equality or 
 *    equivalence and a representation of equivalence on some type. This 
 *    trait is for representing the latter.  
 *  
 *  
 *    An equivalence 
 *    relation is a binary relation on a type. This relation is exposed as
 *    the equiv method of the Equiv trait. This
 *    relation must be:
 *  
 *  
 *   reflexive: equiv(x, x) == true, for any x of 
 *     type T.
 *   symmetric: equiv(x, y) == equiv(y, x), for any
 *     x and y of type T.
 *   transitive: if equiv(x, y) == true and equiv(y, z) == true 
 *     then equiv(x, z) == true, for any x, y,
 *     and z of type T.
 *  
 *
 *  @author  Geoffrey Washburn
 *  @version 1.0, 2008-04-03
 *  @since 2.7
 */

trait Equiv[T] {
  /** Returns true iff x is equivalent to
   *  y.  
   */
  def equiv(x: T, y: T): Boolean 
}