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Metamath Proof Explorer

Theorem tsetndxnn

Description: The index of the slot for the group operation in an extensible structure is a positive integer. (Contributed by AV, 31-Oct-2024)

		Ref	Expression
	Assertion	tsetndxnn	$⊢ TopSet (ndx) \in ℕ$

Step	Hyp	Ref	Expression
1		tsetndx	$⊢ TopSet (ndx) = 9$
2		9nn	$⊢ 9 \in ℕ$
3	1 2	eqeltri	$⊢ TopSet (ndx) \in ℕ$