requisite variety

基本解释

Variety purity test is the requisite for variety protection and seed production of maize, which plays great role in maize production.
品种纯度检验是玉米新品种保护及种子生产的技术依据，对玉米生产具有重要影响。
There seems to be a "requisite variety" -- a minimum complexity or diversity of parts -- for such processes as self-organization, evolution, learning, and life.
似乎存在着一种“必需的多样性”――一种最小限度的复杂性或个体间的差异――适用于诸如自我组织、进化、学习和生死这些过程。
In his Law of Requisite Variety, Ashby pointed out that the complexity of a management system would be bound to correspond to the complexity of the controlled object system.
阿什比的“必要的多样性”定律指出，管理系统的复杂性需要与管理对象系统的复杂性相适应。

Of course, there are the requisite spa treatments (almost uniformly outstanding) and fitness classes, and much to Miraval's credit, the variety and availability of both make it easy to cram your day full of activities rather than wait around for that one afternoon slot for the hot-stone massage.
FORBES: Magazine Article