- #1
mathmari
Gold Member
MHB
- 5,049
- 7
Hey!
Let $X$ be a set. We consider the map \begin{equation*}\Phi : \ \mathcal{P}(X)\rightarrow \{0,1\}^X, \ \ A\mapsto 1_A\end{equation*} that maps a subset $A\subset X$to its characteristc function $1_A$.
I want to show in the following two ways that $\Phi$ is bijective:
Could you give me a hint how we can show that? I don't really have an idea. (Wondering)
Let $X$ be a set. We consider the map \begin{equation*}\Phi : \ \mathcal{P}(X)\rightarrow \{0,1\}^X, \ \ A\mapsto 1_A\end{equation*} that maps a subset $A\subset X$to its characteristc function $1_A$.
I want to show in the following two ways that $\Phi$ is bijective:
- verify directly that $\Phi$ is injective and surjective
- give explicitly an inverse map
Could you give me a hint how we can show that? I don't really have an idea. (Wondering)