Theorem intnan

Description: Introduction of conjunct inside of a contradiction. (Contributed by NM, 16-Sep-1993)

	Ref	Expression
Hypothesis	intnan.1	$$⊢\neg \phi$$
Assertion	intnan	$$⊢\neg \left(\psi \wedge \phi \right)$$

Proof

Step	Hyp	Ref	Expression
1		intnan.1	$$⊢\neg \phi$$
2		simpr	$$⊢\left(\psi \wedge \phi \right)\to \phi$$
3	1 2	mto	$$⊢\neg \left(\psi \wedge \phi \right)$$