match l1, l2 with
| Terms.Predicate p1, Terms.Predicate p2 -> compare_foterm p1 p2
| Terms.Equation (l1,r1,ty1,o1), Terms.Equation (l2,r2,ty2,o2) ->
match l1, l2 with
| Terms.Predicate p1, Terms.Predicate p2 -> compare_foterm p1 p2
| Terms.Equation (l1,r1,ty1,o1), Terms.Equation (l2,r2,ty2,o2) ->