noun
Pareto optimum; Pareto efficiency
Technical term in economics and game theory for a state where no individual can be made better off without making someone else worse off.
パレート最適な状態では、誰かの効用を上げるには他の誰かの効用を下げなければならない。
In a Pareto optimal state, to increase one person's utility you must decrease another's.
パレート改善 is a change that makes at least one person better off without making anyone worse off, while パレート最適 is the state where no further such improvements are possible.
From Italian economist Vilfredo Pareto's name + 最適 (optimum).