Theorem
pm2.521g
A general instance of Theorem *2.521 of [WhiteheadRussell] p. 107. (Contributed by BJ, 28-Oct-2023.)
Conclusion
\( \vdash \neg (\varphi \rightarrow \psi) \rightarrow \psi \rightarrow \chi \)
Proof
conax1
pm2.21d
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