content: /*
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements.  See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file to you under the Apache License, Version 2.0
   * (the "License"); you may not use this file except in compliance with
   * the License.  You may obtain a copy of the License at
   *
   * http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  /**
   * Defines logical relational expressions.
   *
   * <h2>Related packages and classes</h2>
   * <ul>
   *
   * <li>Package <code>
   * <a href="../logical/package-summary.html">org.apache.calcite.rel.core</a></code>
   * contains core relational expressions
   *
   * <li>Package <code>
   * <a href="../package-summary.html">org.apache.calcite.rex</a></code>
   * defines the relational expression API
   *
   * </ul>
   */
  package org.apache.calcite.rel.logical;
  