protected boolean collectInconsistency(Derivation inconsistency){
  for (  Fact source : inconsistency.getSources()) {
    if (frontier(source)) {
      return inconsistencies.add(inconsistency);
    }
  }
  return false;
}

protected boolean collectInconsistency ( Derivation inconsistency ) { for ( Fact source : inconsistency . getSources ( ) ) { if ( frontier ( source ) ) { return inconsistencies . add ( inconsistency ) ; } } return false ; }
store inconsistency if it really is new .
