Metamath Proof Explorer


Theorem neg1z

Description: -1 is an integer. (Contributed by David A. Wheeler, 5-Dec-2018)

Ref Expression
Assertion neg1z
|- -u 1 e. ZZ

Proof

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