Theorem con1biidc 889

Description: A contraposition inference. (Contributed by Jim Kingdon, 15-Mar-2018.)

Hypothesis

Ref	Expression
con1biidc.1	⊢ (DECID 𝜑 → (¬ 𝜑 ↔ 𝜓))

Assertion

Ref	Expression
con1biidc	⊢ (DECID 𝜑 → (¬ 𝜓 ↔ 𝜑))

Proof of Theorem con1biidc

Step	Hyp	Ref	Expression
1		notnotbdc 884	. . 3 ⊢ (DECID 𝜑 → (𝜑 ↔ ¬ ¬ 𝜑))
2		con1biidc.1	. . . 4 ⊢ (DECID 𝜑 → (¬ 𝜑 ↔ 𝜓))
3	2	notbid 677	. . 3 ⊢ (DECID 𝜑 → (¬ ¬ 𝜑 ↔ ¬ 𝜓))
4	1, 3	bitrd 188	. 2 ⊢ (DECID 𝜑 → (𝜑 ↔ ¬ 𝜓))
5	4	bicomd 141	1 ⊢ (DECID 𝜑 → (¬ 𝜓 ↔ 𝜑))

This proof depends on syntax axioms:  ¬ wn 3   → wi 4   ↔ wb 105  DECID wdc 846

This proof depends on axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-in1 623  ax-in2 624  ax-io 721

This proof depends on definitions:  df-bi 117  df-dc 847

This theorem is used by:  con2biidc  891  necon1abiidc  2480  necon1bbiidc  2481