Theorem exbiri

Inference form of [exbir]. This proof is [exbiriVD] automatically translated and minimized. (Contributed by Alan Sare, 31-Dec-2011.) (Proof shortened by Wolf Lammen, 27-Jan-2013.)

Hypothesis
exbiri.1
\( \vdash \varphi \wedge \psi \rightarrow (\chi \leftrightarrow \theta) \)
Conclusion
\( \vdash \varphi \rightarrow \psi \rightarrow \theta \rightarrow \chi \)
Proof
exbiri.1
biimpar _
exp31 _