Description: -1 is an integer. (Contributed by David A. Wheeler, 5-Dec-2018)
Ref | Expression | ||
---|---|---|---|
Assertion | neg1z | |- -u 1 e. ZZ |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | 1nn | |- 1 e. NN |
|
2 | nnnegz | |- ( 1 e. NN -> -u 1 e. ZZ ) |
|
3 | 1 2 | ax-mp | |- -u 1 e. ZZ |