package org.w3c.rdf.model;/** * An RDF model that natively supports set operations `union', `difference' and `intersection'. * * @see org.w3c.rdf.util.SetOperations */public interface SetModel extends Model {  /**   * Set union with another model.   * @return  <code>this</code>, i.e. the model itself   */  public SetModel unite(Model m) throws ModelException;  /**   * Set difference with another model.   * @return  <code>this</code>, i.e. the model itself   */  public SetModel subtract(Model m) throws ModelException;  /**   * Set intersection with another model.   * @return  <code>this</code>, i.e. the model itself   */  public SetModel intersect(Model m) throws ModelException;}