Theorem unifndx

Description: Index value of the df-unif slot. (Contributed by Thierry Arnoux, 17-Dec-2017)

	Ref	Expression
Assertion	unifndx	$$⊢\mathrm{UnifSet}\left(\mathrm{ndx}\right)=13$$

Proof

Step	Hyp	Ref	Expression
1		df-unif	$$⊢\mathrm{UnifSet}=\mathrm{Slot}13$$
2		1nn0	$$⊢1\in {\mathbb{N}}_0$$
3		3nn	$$⊢3\in \mathbb{N}$$
4	2 3	decnncl	$$⊢13\in \mathbb{N}$$
5	1 4	ndxarg	$$⊢\mathrm{UnifSet}\left(\mathrm{ndx}\right)=13$$