EDB — 03P

Exercises

1. [03P] Prerequisites: [036]↺↻,[03H]↺↻.

   Let $A_0.A_1\dots A_n\dots$ sets of countable cardinality, for $n\in \mathbb{N}$.

   Show that $B=\bigcup _{k=0}^{\mathrm{\infty }}{A}_k$ is countable.

   Note that $B$ is infinite-countable if for example there is at least one $n$ for which $A_n$ is infinite-countable.

   Solution 1

   [03Q]↺↻