public ConjunctionOfClauses extend(Collection<Clause> additionalClauses){
  Set<Clause> extendedClauses=new LinkedHashSet<Clause>();
  extendedClauses.addAll(clauses);
  extendedClauses.addAll(additionalClauses);
  ConjunctionOfClauses result=new ConjunctionOfClauses(extendedClauses);
  return result;
}

public ConjunctionOfClauses extend ( Collection < Clause > additionalClauses ) { Set < Clause > extendedClauses = new LinkedHashSet < Clause > ( ) ; extendedClauses . addAll ( clauses ) ; extendedClauses . addAll ( additionalClauses ) ; ConjunctionOfClauses result = new ConjunctionOfClauses ( extendedClauses ) ; return result ; }
create a new conjunction of clauses by taking the clauses from the current conjunction and adding additional clauses to it .
