Metamath Proof Explorer

Theorem bnj258

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

		Ref	Expression
	Assertion	bnj258	$⊢ (φ \land ψ \land χ \land θ) \leftrightarrow ((φ \land ψ \land θ) \land χ)$

Step	Hyp	Ref	Expression
1		bnj257	$⊢ (φ \land ψ \land χ \land θ) \leftrightarrow (φ \land ψ \land θ \land χ)$
2		df-bnj17	$⊢ (φ \land ψ \land θ \land χ) \leftrightarrow ((φ \land ψ \land θ) \land χ)$
3	1 2	bitri	$⊢ (φ \land ψ \land χ \land θ) \leftrightarrow ((φ \land ψ \land θ) \land χ)$