(datatype Node
 (mk i64))

(relation edge (Node Node))
(relation path (Node Node))
            
(rule ((edge x y))
      ((path x y)))

(rule ((path x y) (edge y z))
      ((path x z)))

(edge (mk 1) (mk 2))
(edge (mk 2) (mk 3))
(edge (mk 5) (mk 6))

(union (mk 3) (mk 5))

(run 10)
(check (edge (mk 3) (mk 6)))
(check (path (mk 1) (mk 6)))