code: ///////////////////////////////////////////////////////////////////////////
  //                   __                _      _   ________               //
  //                  / /   ____  ____ _(_)____/ | / / ____/               //
  //                 / /   / __ \/ __ `/ / ___/  |/ / / __                 //
  //                / /___/ /_/ / /_/ / / /__/ /|  / /_/ /                 //
  //               /_____/\____/\__, /_/\___/_/ |_/\____/                  //
  //                           /____/                                      //
  //                                                                       //
  //               The Next Generation Logic Library                       //
  //                                                                       //
  ///////////////////////////////////////////////////////////////////////////
  //                                                                       //
  //  Copyright 2015-20xx Christoph Zengler                                //
  //                                                                       //
  //  Licensed under the Apache License, Version 2.0 (the "License");      //
  //  you may not use this file except in compliance with the License.     //
  //  You may obtain a copy of the License at                              //
  //                                                                       //
  //  http://www.apache.org/licenses/LICENSE-2.0                           //
  //                                                                       //
  //  Unless required by applicable law or agreed to in writing, software  //
  //  distributed under the License is distributed on an "AS IS" BASIS,    //
  //  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or      //
  //  implied.  See the License for the specific language governing        //
  //  permissions and limitations under the License.                       //
  //                                                                       //
  ///////////////////////////////////////////////////////////////////////////
  
  package org.logicng.explanations;
  
  import org.logicng.propositions.Proposition;
  
  import java.util.List;
  import java.util.Objects;
  
  /**
   * An unsatisfiable core (can be a minimal unsatisfiable sub-formula).
   * @param <T> the type of the core's propositions
   * @version 1.3
   * @since 1.1
   */
  public final class UNSATCore<T extends Proposition> {
  
      private final List<T> propositions;
      private final boolean isMUS;
  
      /**
       * Constructs a new unsatisfiable core.
       * @param propositions the propositions of the core
       * @param isMUS        {@code true} if it is a MUS and {@code false} if it is unknown whether it is a MUS.
       */
      public UNSATCore(final List<T> propositions, final boolean isMUS) {
          this.propositions = propositions;
          this.isMUS = isMUS;
      }
  
      /**
       * Returns the propositions of this MUS.
       * @return the propositions of this MUS
       */
      public List<T> propositions() {
          return this.propositions;
      }
  
      /**
       * Returns {@code true} if this core is a MUS and {@code false} if it is unknown whether it is a MUS.
       * Note, if set to {@code false} this core might be a MUS, but it is not yet verified.
       * @return {@code true} if this core is a MUS and {@code false} if it is unknown whether it is a MUS.
       */
      public boolean isMUS() {
          return this.isMUS;
      }
  
      @Override
      public int hashCode() {
          return Objects.hash(this.propositions, this.isMUS);
      }
  
      @Override
      public boolean equals(final Object o) {
          if (this == o) {
              return true;
          }
          if (!(o instanceof UNSATCore)) {
              return false;
          }
          final UNSATCore<?> unsatCore = (UNSATCore<?>) o;
          return this.isMUS == unsatCore.isMUS && Objects.equals(this.propositions, unsatCore.propositions);
      }
  
      @Override
      public String toString() {
          return String.format("UNSATCore{isMUS=%s, propositions=%s}", this.isMUS, this.propositions);
      }
  }
  