Theorem bijadc 877

Description: Combine antecedents into a single biconditional. This inference is reminiscent of jadc 858. (Contributed by Jim Kingdon, 4-May-2018.)

Hypotheses

Ref	Expression
bijadc.1	⊢ (𝜑 → (𝜓 → 𝜒))
bijadc.2	⊢ (¬ 𝜑 → (¬ 𝜓 → 𝜒))

Assertion

Ref	Expression
bijadc	⊢ (DECID 𝜓 → ((𝜑 ↔ 𝜓) → 𝜒))

Proof of Theorem bijadc

Step	Hyp	Ref	Expression
1		biimpr 129	. . 3 ⊢ ((𝜑 ↔ 𝜓) → (𝜓 → 𝜑))
2		bijadc.1	. . 3 ⊢ (𝜑 → (𝜓 → 𝜒))
3	1, 2	syli 37	. 2 ⊢ ((𝜑 ↔ 𝜓) → (𝜓 → 𝜒))
4		biimp 117	. . . 4 ⊢ ((𝜑 ↔ 𝜓) → (𝜑 → 𝜓))
5	4	con3d 626	. . 3 ⊢ ((𝜑 ↔ 𝜓) → (¬ 𝜓 → ¬ 𝜑))
6		bijadc.2	. . 3 ⊢ (¬ 𝜑 → (¬ 𝜓 → 𝜒))
7	5, 6	syli 37	. 2 ⊢ ((𝜑 ↔ 𝜓) → (¬ 𝜓 → 𝜒))
8	3, 7	pm2.61ddc 856	1 ⊢ (DECID 𝜓 → ((𝜑 ↔ 𝜓) → 𝜒))

Syntax hints:  ¬ wn 3   → wi 4   ↔ wb 104  DECID wdc 829

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-in1 609  ax-in2 610  ax-io 704

This theorem depends on definitions:  df-bi 116  df-dc 830

This theorem is referenced by: (None)