return isDirected() == other.isDirected()
        && nodes().equals(other.nodes())
        && edgeIncidentNodesMap(this).equals(edgeIncidentNodesMap(other));
  }

  @Override
  public final int hashCode() {
    return edgeIncidentNodesMap(this).hashCode();
  }

  /** Returns a string representation of this network. */
  @Override
  public String toString() {