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Metamath Proof Explorer

Theorem funtopon

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

		Ref	Expression
	Assertion	funtopon	$⊢ Fun TopOn$

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