content: /**
   * Copyright (c) 2018-2019 Siemens AG
   * All rights reserved.
   * 
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are met:
   * 
   * 1) Redistributions of source code must retain the above copyright notice, this
   *    list of conditions and the following disclaimer.
   * 
   * 2) Redistributions in binary form must reproduce the above copyright notice,
   *    this list of conditions and the following disclaimer in the documentation
   *    and/or other materials provided with the distribution.
   * 
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
   * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
   * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
   * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  package at.ac.tuwien.kr.alpha.core.solver.heuristics;
  
  import at.ac.tuwien.kr.alpha.api.config.BinaryNoGoodPropagationEstimationStrategy;
  import at.ac.tuwien.kr.alpha.core.solver.BinaryNoGoodPropagationEstimation;
  
  /**
   * The well-known MOMs (Maximum Occurrences in clauses of Minimum size) heuristic
   * used to initialize atom scores.
   * This implementation is inspired by the MOMs implementation in <a href="https://github.com/potassco/clasp">clasp</a>
   * but differs from it in several ways, e.g.:
   * <ul>
   * 	<li>The default strategy is {@link BinaryNoGoodPropagationEstimationStrategy#CountBinaryWatches}, not {@link BinaryNoGoodPropagationEstimationStrategy#BinaryNoGoodPropagation}.</li>
   * 	<li>{@link BinaryNoGoodPropagationEstimationStrategy#BinaryNoGoodPropagation} does not do only one iteration of propagation, but exhaustive propagation.</li>
   * </ul>
   *
   */
  public class MOMs {
  	
  	static final BinaryNoGoodPropagationEstimationStrategy DEFAULT_STRATEGY = BinaryNoGoodPropagationEstimationStrategy.CountBinaryWatches;
  	
  	private BinaryNoGoodPropagationEstimation bnpEstimation;
  	private BinaryNoGoodPropagationEstimationStrategy strategy = DEFAULT_STRATEGY;
  
  	public MOMs(BinaryNoGoodPropagationEstimation bnpEstimation) {
  		super();
  		this.bnpEstimation = bnpEstimation;
  	}
  
  	/**
  	 * @param atom
  	 * @return
  	 */
  	public double getScore(Integer atom) {
  		int s1 = bnpEstimation.estimate(atom, true, strategy);
  		int s2 = bnpEstimation.estimate(atom, false, strategy);
  		return ((s1 * s2) << 10) + s1 + s2;
  	}
  
  	public void setStrategy(BinaryNoGoodPropagationEstimationStrategy strategy) {
  		this.strategy = strategy != null ? strategy : DEFAULT_STRATEGY;
  	}
  
  }
  