Theorem funtopon

Description: The class TopOn is a function. (Contributed by BJ, 29-Apr-2021)

	Ref	Expression
Assertion	funtopon	$$⊢\mathrm{Fun}\mathrm{TopOn}$$

Proof

Step	Hyp	Ref	Expression
1		df-topon	$$⊢\mathrm{TopOn}=\left(y\in \mathrm{V}⟼\left\{x\in \mathrm{Top}|y=\bigcup x\right\}\right)$$
2	1	funmpt2	$$⊢\mathrm{Fun}\mathrm{TopOn}$$