Metamath Proof Explorer

Theorem nottru

Description: A -. identity. (Contributed by Anthony Hart, 22-Oct-2010)

Ref Expression
Assertion nottru ⊢ ¬ ⊤ ↔ ⊥

Proof

Step Hyp Ref Expression
1 df-fal ⊢ ⊥ ↔ ¬ ⊤
2 1 bicomi ⊢ ¬ ⊤ ↔ ⊥