Description: Commutation of antecedents. Swap 1st and 4th. (Contributed by NM, 25-Apr-1994) (Proof shortened by Wolf Lammen, 28-Jul-2012)
Ref | Expression | ||
---|---|---|---|
Hypothesis | com4.1 | ||
Assertion | com14 |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | com4.1 | ||
2 | 1 | com4l | |
3 | 2 | com3r |