intersection (C l1 (Regular u1)) (C l2 (Regular u2)) = finiteBar (max l1 l2) (min u1 u2)
intersection (C l1 (Regular u1)) (C l2 (Regular u2)) = finiteBar (max l1 l2) (min u1 u2)
intersection (C l1 (Regular u1)) (C l2 (Regular u2)) = finiteBar (max l1 l2) (min u1 u2)