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Theorem xorcomOLD 1506
Description: Obsolete version of xorcom 1505 as of 21-Apr-2024. (Contributed by Mario Carneiro, 4-Sep-2016.) (Proof modification is discouraged.) (New usage is discouraged.)
Assertion
Ref Expression
xorcomOLD ((𝜑𝜓) ↔ (𝜓𝜑))

Proof of Theorem xorcomOLD
StepHypRef Expression
1 bicom 225 . . 3 ((𝜑𝜓) ↔ (𝜓𝜑))
21notbii 323 . 2 (¬ (𝜑𝜓) ↔ ¬ (𝜓𝜑))
3 df-xor 1503 . 2 ((𝜑𝜓) ↔ ¬ (𝜑𝜓))
4 df-xor 1503 . 2 ((𝜓𝜑) ↔ ¬ (𝜓𝜑))
52, 3, 43bitr4i 306 1 ((𝜑𝜓) ↔ (𝜓𝜑))
Colors of variables: wff setvar class
Syntax hints:  ¬ wn 3  wb 209  wxo 1502
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8
This theorem depends on definitions:  df-bi 210  df-xor 1503
This theorem is referenced by: (None)
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