Theorem anass

Associative law for conjunction. Theorem *4.32 of [WhiteheadRussell] p. 118. (Contributed by NM, 21-Jun-1993.) (Proof shortened by Wolf Lammen, 24-Nov-2012.)

Conclusion
\( \vdash \varphi \wedge \psi \wedge \chi \leftrightarrow \varphi \wedge (\psi \wedge \chi) \)
Proof
id
l1
anassrs _
id
anasss _
impbii l1 _