Error: Underscore in binary relation in file subsumption.dl at line 85
   list = [i, _],
---^--------------
Warning: Variable l1 only occurs once in file subsumption.dl at line 86
   i = [l1, u1],
--------^--------
Warning: Variable u2 only occurs once in file subsumption.dl at line 87
   y = [l2, u2],
------------^----
Warning: Variable tail only occurs once in file subsumption.dl at line 106
   list = [i, tail],
--------------^------
Warning: Variable u2 only occurs once in file subsumption.dl at line 108
   y = [l2, u2],
------------^----
Warning: Variable tail only occurs once in file subsumption.dl at line 118
   list = [i, tail],
--------------^------
1 errors generated, evaluation aborted
