Theorem pm1.5

Axiom *1.5 (Assoc) of [WhiteheadRussell] p. 96. (Contributed by NM, 3-Jan-2005.)

Conclusion
\( \vdash \varphi \vee (\psi \vee \chi) \rightarrow \psi \vee (\varphi \vee \chi) \)
Proof
orc
l1
olcd _
olc
orim2i _
jaoi l1 _