Theorem plusgndxnn

Description: The index of the slot for the group operation in an extensible structure is a positive integer. (Contributed by AV, 17-Oct-2024)

	Ref	Expression
Assertion	plusgndxnn	$$⊢{+}_{\mathrm{ndx}}\in \mathbb{N}$$

Proof

Step	Hyp	Ref	Expression
1		plusgndx	$$⊢{+}_{\mathrm{ndx}}=2$$
2		2nn	$$⊢2\in \mathbb{N}$$
3	1 2	eqeltri	$$⊢{+}_{\mathrm{ndx}}\in \mathbb{N}$$