如果是unionexpression类，evaluate方法将对两个操作数求值，检查在这两种情况下节点集的结果，然后使用排序合并策略组成联合。
In the case of the UnionExpression class, the evaluate method evaluates the two operands, checks that the result is in both cases a node-set, and then forms the union using a sort-merge strategy.
在典型的测试函数集上的数值实验结果表明，根据这些策略改进的算法得到的非劣解集具有较好的分布性，同时收敛速度更快。
The simulations prove that the non-dominated Pareto optimal solutions have better distribution and faster convergence at the same time in typical functions.
在典型的测试函数集上的数值实验结果表明，根据这些策略改进的算法得到的非劣解集具有较好的分布性，同时收敛速度更快。
The simulations prove that the non-dominated Pareto optimal solutions have better distribution and faster convergence at the same time in typical functions.
应用推荐