Theorem bnj250

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

	Ref	Expression
Assertion	bnj250	|- ( ( 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		3anass	|- ( ( ph /\ ps /\ ch ) <-> ( ph /\ ( ps /\ ch ) ) )
3	2	anbi1i	|- ( ( ( ph /\ ps /\ ch ) /\ th ) <-> ( ( ph /\ ( ps /\ ch ) ) /\ th ) )
4		anass	|- ( ( ( ph /\ ( ps /\ ch ) ) /\ th ) <-> ( ph /\ ( ( ps /\ ch ) /\ th ) ) )
5	1 3 4	3bitri	|- ( ( ph /\ ps /\ ch /\ th ) <-> ( ph /\ ( ( ps /\ ch ) /\ th ) ) )