Theorem pm2.53 723

Description: Theorem *2.53 of [WhiteheadRussell] p. 107. This holds intuitionistically, although its converse does not (see pm2.54dc 892). (Contributed by NM, 3-Jan-2005.) (Revised by NM, 31-Jan-2015.)

Assertion

Ref	Expression
pm2.53	⊢ ((𝜑 ∨ 𝜓) → (¬ 𝜑 → 𝜓))

Proof of Theorem pm2.53

Step	Hyp	Ref	Expression
1		pm2.24 622	. 2 ⊢ (𝜑 → (¬ 𝜑 → 𝜓))
2		ax-1 6	. 2 ⊢ (𝜓 → (¬ 𝜑 → 𝜓))
3	1, 2	jaoi 717	1 ⊢ ((𝜑 ∨ 𝜓) → (¬ 𝜑 → 𝜓))

Syntax hints:  ¬ wn 3   → wi 4   ∨ wo 709

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-in2 616  ax-io 710

This theorem depends on definitions:  df-bi 117

This theorem is referenced by:  ori  724  ord  725  orel1  726  pm2.63  801  notnotrdc  844  dfordc  893  pm5.6r  928  xorbin  1395  19.33b2  1640  r19.30dc  2637  onsucelsucexmid  4550  oprabidlem  5931  omnimkv  7189  xnn0nnn0pnf  9287  absle  11139