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Metamath Proof Explorer


Theorem an21

Description: Swap two conjuncts. (Contributed by Peter Mazsa, 18-Sep-2022)

Ref Expression
Assertion an21 φ ψ χ ψ φ χ

Proof

Step Hyp Ref Expression
1 biid φ χ φ χ
2 1 bianassc ψ φ χ φ ψ χ
3 2 bicomi φ ψ χ ψ φ χ