Theorem pm2.62

Theorem *2.62 of [WhiteheadRussell] p. 107. (Contributed by NM, 3-Jan-2005.) (Proof shortened by Wolf Lammen, 13-Dec-2013.)

Conclusion

\( \vdash \varphi \vee \psi \rightarrow (\varphi \rightarrow \psi) \rightarrow \psi \)

Proof

pm2.621

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