Theorem bj-bijust0ALT

Description: Alternate proof of bijust0 ; shorter but using additional intermediate results. (Contributed by NM, 11-May-1999) (Proof shortened by Josh Purinton, 29-Dec-2000) (Revised by BJ, 19-Mar-2020) (Proof modification is discouraged.) (New usage is discouraged.)

	Ref	Expression
Assertion	bj-bijust0ALT	$$⊢\neg \left(\left(\phi \to \phi \right)\to \neg \left(\phi \to \phi \right)\right)$$

Proof

Step	Hyp	Ref	Expression
1		id	$$⊢\phi \to \phi$$
2	1	bj-nimni	$$⊢\neg \left(\left(\phi \to \phi \right)\to \neg \left(\phi \to \phi \right)\right)$$