Metamath Proof Explorer

Theorem 3anrev

Description: Reversal law for triple conjunction. (Contributed by NM, 21-Apr-1994)

Ref Expression
Assertion 3anrev 
|- ( ( ph /\ ps /\ ch ) <-> ( ch /\ ps /\ ph ) )

Proof

Step Hyp Ref Expression
1 3ancoma 
 |-  ( ( ph /\ ps /\ ch ) <-> ( ps /\ ph /\ ch ) )
2 3anrot 
 |-  ( ( ch /\ ps /\ ph ) <-> ( ps /\ ph /\ ch ) )
3 1 2 bitr4i 
 |-  ( ( ph /\ ps /\ ch ) <-> ( ch /\ ps /\ ph ) )