Metamath Proof Explorer


Theorem nfneg

Description: Bound-variable hypothesis builder for the negative of a complex number. (Contributed by NM, 12-Jun-2005) (Revised by Mario Carneiro, 15-Oct-2016)

Ref Expression
Hypothesis nfneg.1 𝑥 𝐴
Assertion nfneg 𝑥 - 𝐴

Proof

Step Hyp Ref Expression
1 nfneg.1 𝑥 𝐴
2 1 a1i ( ⊤ → 𝑥 𝐴 )
3 2 nfnegd ( ⊤ → 𝑥 - 𝐴 )
4 3 mptru 𝑥 - 𝐴