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negneg1e1
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Metamath Proof Explorer
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Theorem
negneg1e1
Description:
-u -u 1
is 1.
(Contributed by
David A. Wheeler
, 8-Dec-2018)
Ref
Expression
Assertion
negneg1e1
$${\u22a2}--1=1$$
Proof
Step
Hyp
Ref
Expression
1
ax-1cn
$${\u22a2}1\in \u2102$$
2
1
negnegi
$${\u22a2}--1=1$$