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package lamps.metrics;

/**
 *
 * @author hokipka
 */
/**
 * The <code>Proximity</code> interface provides a general method for defining
 * closeness between two objects. Proximity is a similarity measure, with two
 * objects having higher proximity being more similar to one another. It
 * provides a single method {@link
 * #proximity(Object,Object)} returning the proximity between two objects. The
 * closer two objects are, the higher their proximity value.
 *
 * <p>
 * Proximity runs in the other direction from distance. With distance, the
 * closer two objects are, the lower their distance value. Many classes
 * implement both <code>Proximity</code> and {@link Distance}, with one method
 * defined in terms of the other. For instance, negation converts a distance
 * into a proximity.
 *
 * @author Bob Carpenter
 * @version 3.0
 * @since LingPipe3.0
 * @param <E> the type of objects between which proximity is defined
 */
public interface Proximity<E> {

    /**
     * Returns the distance between the specified pair of objects.
     *
     * @param e1 First object.
     * @param e2 Second object.
     * @return Proximity between the two objects.
     */
    public double proximity(E e1, E e2);

}