Description: A positive integer is greater than zero. (Contributed by Scott Fenton, 15-Apr-2025)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | nnsgt0 | |- ( A e. NN_s -> 0s | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 1 | nnssn0s | |- NN_s C_ NN0_s | |
| 2 | 1 | sseli | |- ( A e. NN_s -> A e. NN0_s ) | 
| 3 | n0sge0 | |- ( A e. NN0_s -> 0s <_s A ) | |
| 4 | 2 3 | syl | |- ( A e. NN_s -> 0s <_s A ) | 
| 5 | nnne0s | |- ( A e. NN_s -> A =/= 0s ) | |
| 6 | 0sno | |- 0s e. No | |
| 7 | 6 | a1i | |- ( A e. NN_s -> 0s e. No ) | 
| 8 | nnsno | |- ( A e. NN_s -> A e. No ) | |
| 9 | 7 8 | sltlend | |- ( A e. NN_s -> ( 0s | 
| 10 | 4 5 9 | mpbir2and | |- ( A e. NN_s -> 0s |