Metamath Proof Explorer


Theorem exmidne

Description: Excluded middle with equality and inequality. (Contributed by NM, 3-Feb-2012) (Proof shortened by Wolf Lammen, 17-Nov-2019)

Ref Expression
Assertion exmidne ⊢ A = B ∨ A ≠ B

Proof

Step Hyp Ref Expression
1 neqne ⊢ ¬ A = B → A ≠ B
2 1 orri ⊢ A = B ∨ A ≠ B