Theorem bnj255

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

	Ref	Expression
Assertion	bnj255	|- ( ( ph /\ ps /\ ch /\ th ) <-> ( ph /\ ps /\ ( ch /\ th ) ) )

Proof

Step	Hyp	Ref	Expression
1		bnj251	|- ( ( ph /\ ps /\ ch /\ th ) <-> ( ph /\ ( ps /\ ( ch /\ th ) ) ) )
2		3anass	|- ( ( ph /\ ps /\ ( ch /\ th ) ) <-> ( ph /\ ( ps /\ ( ch /\ th ) ) ) )
3	1 2	bitr4i	|- ( ( ph /\ ps /\ ch /\ th ) <-> ( ph /\ ps /\ ( ch /\ th ) ) )