Theorem simplim

Description: Simplification. Similar to Theorem *3.26 (Simp) of WhiteheadRussell p. 112. (Contributed by NM, 3-Jan-1993) (Proof shortened by Wolf Lammen, 21-Jul-2012)

	Ref	Expression
Assertion	simplim	$$⊢\neg \left(\phi \to \psi \right)\to \phi$$

Proof

Step	Hyp	Ref	Expression
1		pm2.21	$$⊢\neg \phi \to \left(\phi \to \psi \right)$$
2	1	con1i	$$⊢\neg \left(\phi \to \psi \right)\to \phi$$