第 1 步，共 12 步8%

Predicates and Variables

谓词是带有变量的陈述模板。P(x) 可以表示“x 是偶数”。只有当我们用一个具体的值代入 x 时，它才成为命题。

Predicate: P(x) = 'x is a prime number'

  • P(3) is true
  • P(4) is false
  • P(x) alone is neither true nor false — it depends on x

Predicates extend propositional logic by adding variables and quantifiers.

提示

检验你的理解

Is P(x) = 'x > 5' a proposition by itself?