Theorem annimim 815

Description: Express conjunction in terms of implication. One direction of Theorem *4.61 of [WhiteheadRussell] p. 120. The converse holds for decidable propositions, as can be seen at annimdc 878. (Contributed by Jim Kingdon, 24-Dec-2017.)

Assertion

Ref	Expression
annimim	⊢ ((𝜑 ∧ ¬ 𝜓) → ¬ (𝜑 → 𝜓))

Proof of Theorem annimim

Step	Hyp	Ref	Expression
1		pm2.27 39	. . 3 ⊢ (𝜑 → ((𝜑 → 𝜓) → 𝜓))
2		con3 603	. . 3 ⊢ (((𝜑 → 𝜓) → 𝜓) → (¬ 𝜓 → ¬ (𝜑 → 𝜓)))
3	1, 2	syl 14	. 2 ⊢ (𝜑 → (¬ 𝜓 → ¬ (𝜑 → 𝜓)))
4	3	imp 122	1 ⊢ ((𝜑 ∧ ¬ 𝜓) → ¬ (𝜑 → 𝜓))

Syntax hints:  ¬ wn 3   → wi 4   ∧ wa 102

This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 104  ax-ia2 105  ax-in1 576  ax-in2 577

This theorem is referenced by:  pm4.65r  816  dcim  817  imanim  818  pm4.52im  836  exanaliim  1578