Metamath Proof Explorer

Theorem nnnn0i

Description: A positive integer is a nonnegative integer. (Contributed by NM, 20-Jun-2005)

Ref Expression
Hypothesis nnnn0i.1 
|- N e. NN
Assertion nnnn0i 
|- N e. NN0

Proof

Step Hyp Ref Expression
1 nnnn0i.1 
 |-  N e. NN
2 nnnn0 
 |-  ( N e. NN -> N e. NN0 )
3 1 2 ax-mp 
 |-  N e. NN0