let add_constraint strict a b =
match a,b with
| [false,a2],[false,b2] ->
if not (le_path_uri [] strict a2 b2) then (
if le_path_uri [] (not strict) b2 a2 then
let add_constraint strict a b =
match a,b with
| [false,a2],[false,b2] ->
if not (le_path_uri [] strict a2 b2) then (
if le_path_uri [] (not strict) b2 a2 then