Metamath Proof Explorer


Theorem axorbtnotaiffb

Description: Given a is exclusive to b, there exists a proof for (not (a if-and-only-if b)); df-xor is a closed form of this. (Contributed by Jarvin Udandy, 7-Sep-2016)

Ref Expression
Hypothesis axorbtnotaiffb.1 φ ψ
Assertion axorbtnotaiffb ¬ φ ψ

Proof

Step Hyp Ref Expression
1 axorbtnotaiffb.1 φ ψ
2 df-xor φ ψ ¬ φ ψ
3 1 2 mpbi ¬ φ ψ