Level: Lib Thy Top:
Hypotheses:

None

Conclusion:

T:. L1,L2,L3:T List. L1 @ L2 @ L3 = (L1 @ L2) @ L3

Applied Tactic: UnivCD THENA Auto
Generated subgoals:

1. L1 @ L2 @ L3 = (L1 @ L2) @ L3