Theorem bnj248

Description: /\ -manipulation. (Contributed by Jonathan Ben-Naim, 3-Jun-2011) (New usage is discouraged.)

	Ref	Expression
Assertion	bnj248	|- ( ( ph /\ ps /\ ch /\ th ) <-> ( ( ( ph /\ ps ) /\ ch ) /\ th ) )

Proof

Step	Hyp	Ref	Expression
1		df-bnj17	|- ( ( ph /\ ps /\ ch /\ th ) <-> ( ( ph /\ ps /\ ch ) /\ th ) )
2		df-3an	|- ( ( ph /\ ps /\ ch ) <-> ( ( ph /\ ps ) /\ ch ) )
3	2	anbi1i	|- ( ( ( ph /\ ps /\ ch ) /\ th ) <-> ( ( ( ph /\ ps ) /\ ch ) /\ th ) )
4	1 3	bitri	|- ( ( ph /\ ps /\ ch /\ th ) <-> ( ( ( ph /\ ps ) /\ ch ) /\ th ) )