001    package org.apache.commons.graph;
002    
003    /*
004     * Licensed to the Apache Software Foundation (ASF) under one
005     * or more contributor license agreements.  See the NOTICE file
006     * distributed with this work for additional information
007     * regarding copyright ownership.  The ASF licenses this file
008     * to you under the Apache License, Version 2.0 (the
009     * "License"); you may not use this file except in compliance
010     * with the License.  You may obtain a copy of the License at
011     *
012     *   http://www.apache.org/licenses/LICENSE-2.0
013     *
014     * Unless required by applicable law or agreed to in writing,
015     * software distributed under the License is distributed on an
016     * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
017     * KIND, either express or implied.  See the License for the
018     * specific language governing permissions and limitations
019     * under the License.
020     */
021    
022    /**
023     * An {@code UndirectedGraph} is a graph in which edges have no orientation, i.e., they are not ordered pairs,
024     * but sets <code>{u, v}</code> (or 2-multisets) of vertices.
025     *
026     * @param <V> the Graph vertices type
027     * @param <E> the Graph edges type
028     */
029    public interface UndirectedGraph<V extends Vertex, E extends Edge<V>>
030        extends Graph<V, E>
031    {
032    }