効率性が考慮されるための3条件
https://gyazo.com/9b0f1fd376f63117b65f7fa3f7c934b7
https://gyazo.com/0440632878fd94d7c70f57cf40e02382
https://gyazo.com/2a7656dae3be0b5b16f3b973ae3d7c8e
https://gyazo.com/c8527e1417460efc024456b5fc886a00
https://gyazo.com/38496f8a314313f6fa092a2270ec2362