Theorem truimfal

Description: A -> identity. (Contributed by Anthony Hart, 22-Oct-2010) (Proof shortened by Andrew Salmon, 13-May-2011)

	Ref	Expression
Assertion	truimfal	⊢ ( ( ⊤ → ⊥ ) ↔ ⊥ )

Proof

Step	Hyp	Ref	Expression
1		trut	⊢ ( ⊥ ↔ ( ⊤ → ⊥ ) )
2	1	bicomi	⊢ ( ( ⊤ → ⊥ ) ↔ ⊥ )