Theorem pm2.21d

A contradiction implies anything. Deduction associated with pm2.21. (Contributed by NM, 10-Feb-1996.)

Hypothesis
pm2.21d.1
\( \vdash \varphi \rightarrow \neg \psi \)
Conclusion
\( \vdash \varphi \rightarrow \psi \rightarrow \chi \)
Proof
pm2.21d.1
a1d _
con4d _