Metamath Proof Explorer


Theorem negneg1e1

Description: -u -u 1 is 1. (Contributed by David A. Wheeler, 8-Dec-2018)

Ref Expression
Assertion negneg1e1 -1 = 1

Proof

Step Hyp Ref Expression
1 ax-1cn 1
2 1 negnegi -1 = 1