パレート最適

https://ai-colab.com/2019/05/06/%E7%AC%AC19%E5%9B%9E%E3%80%80%E7%B7%8F%E4%BD%99%E5%89%B0%E3%81%A8%E3%83%91%E3%83%AC%E3%83%BC%E3%83%88%E6%9C%80%E9%81%A9/