Metamath Proof Explorer


Theorem homndx

Description: Index value of the df-hom slot. (Contributed by Mario Carneiro, 7-Jan-2017)

Ref Expression
Assertion homndx ( Hom ‘ ndx ) = 1 4

Proof

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