Metamath Proof Explorer


Theorem ocndx

Description: Index value of the df-ocomp slot. (Contributed by Mario Carneiro, 25-Oct-2015)

Ref Expression
Assertion ocndx ( oc ‘ ndx ) = 1 1

Proof

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