Metamath Proof Explorer


Theorem an13

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

Ref Expression
Assertion an13 φψχχψφ

Proof

Step Hyp Ref Expression
1 an21 ψφχφψχ
2 ancom ψφχχψφ
3 1 2 bitr3i φψχχψφ