Theorem unifndx

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

	Ref	Expression
Assertion	unifndx	⊢ ( UnifSet ‘ ndx ) = ; 1 3

Proof

Step	Hyp	Ref	Expression
1		df-unif	⊢ UnifSet = Slot ; 1 3
2		1nn0	⊢ 1 ∈ ℕ0
3		3nn	⊢ 3 ∈ ℕ
4	2 3	decnncl	⊢ ; 1 3 ∈ ℕ
5	1 4	ndxarg	⊢ ( UnifSet ‘ ndx ) = ; 1 3