Theorem tsetndx

Description: Index value of the df-tset slot. (Contributed by Mario Carneiro, 14-Aug-2015) (New usage is discouraged.)

	Ref	Expression
Assertion	tsetndx	$$⊢\mathrm{TopSet}\left(\mathrm{ndx}\right)=9$$

Proof

Step	Hyp	Ref	Expression
1		df-tset	$$⊢\mathrm{TopSet}=\mathrm{Slot}9$$
2		9nn	$$⊢9\in \mathbb{N}$$
3	1 2	ndxarg	$$⊢\mathrm{TopSet}\left(\mathrm{ndx}\right)=9$$