Metamath Proof Explorer

Theorem nnex

Description: The set of positive integers exists. (Contributed by NM, 3-Oct-1999) (Revised by Mario Carneiro, 17-Nov-2014)

Ref Expression
Assertion nnex 
|- NN e. _V

Proof

Step Hyp Ref Expression
1 cnex 
 |-  CC e. _V
2 nnsscn 
 |-  NN C_ CC
3 1 2 ssexi 
 |-  NN e. _V