Theorem pm2.75

Theorem *2.75 of [WhiteheadRussell] p. 108. (Contributed by NM, 3-Jan-2005.) (Proof shortened by Wolf Lammen, 4-Jan-2013.)

Conclusion

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

Proof

pm2.76

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