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Metamath Proof Explorer


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
|- ( TopSet ` ndx ) = 9

Proof

Step Hyp Ref Expression
1 df-tset
 |-  TopSet = Slot 9
2 9nn
 |-  9 e. NN
3 1 2 ndxarg
 |-  ( TopSet ` ndx ) = 9