Description: A positive integer is an integer. (Contributed by Mario Carneiro, 18-Feb-2014)
Ref | Expression | ||
---|---|---|---|
Hypothesis | nnzi.1 | |- N e. NN |
|
Assertion | nnzi | |- N e. ZZ |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | nnzi.1 | |- N e. NN |
|
2 | nnssz | |- NN C_ ZZ |
|
3 | 2 1 | sselii | |- N e. ZZ |