Metamath Proof Explorer


Theorem an31

Description: A rearrangement of conjuncts. (Contributed by NM, 24-Jun-2012) (Proof shortened by Wolf Lammen, 31-Dec-2012)

Ref Expression
Assertion an31 φ ψ χ χ ψ φ

Proof

Step Hyp Ref Expression
1 an13 φ ψ χ χ ψ φ
2 anass φ ψ χ φ ψ χ
3 anass χ ψ φ χ ψ φ
4 1 2 3 3bitr4i φ ψ χ χ ψ φ