code: public Constraint[] getConstraints(Variable from, Variable to) {
  		Vector<Constraint> ret = new Vector<Constraint>();
  		for (Constraint con : this.getConstraints()) {
  			if (con.getScope().length == 2) {
  				if (con.getScope()[0].equals(from) && con.getScope()[1].equals(to)) ret.add(con);
  			}
  		}
  		return ret.toArray(new Constraint[ret.size()]);
  	}
docs: Get all {@link Constraint}s contained in this {@link ConstraintSolver}'s {@link ConstraintNetwork}
  with given source and destination {@link Variable}s.
  @param from The source {@link Variable} of the {@link Constraint}s to be obtained.
  @param to The destination {@link Variable} of the {@link Constraint}s to be obtained.
  @return The {@link Constraint}s contained in this {@link ConstraintSolver}'s {@link ConstraintNetwork}
  with given source and destination {@link Variable}s.