Definition 1.6. Let K be a perfectoid field. A perfectoid K-algebra is a Banach K-algebra R such that the set of powerbounded elements Rᵒ ⊂ R is bounded, and such that the Frobenius Φ is surjective on Rᵒ/p.
---- 给定完域 K. 完域K-代数 是一个Banach K-代数 R 使得 幂有界子集 Rᵒ ⊂ R 有界,并且 Frobenius Φ 在 Rᵒ/p 上是满的.