摘要：第五周 T1 设 ${x_n}{n = 1}^\infty$ 为有界实数列，$a = \liminf\limits{n \to \infty} x_n, b = \limsup \limits_{n \to \infty} x_n$，满足 $a < b$ 且 $\limsup \limits_{n 阅读全文

摘要：设 $\mathbb{F}, A$ 为两个集合，$\forall x \in \mathbb F, \operatorname{card}(f(x)) = \operatorname{card}(A)$，那么有 $\operatorname{card}(\mathbb F \times A) = \ 阅读全文