let explicit univ =
let conflict_pairs = Hashtbl.create 1023 in
Cudf.iteri_packages (fun i p ->
List.iter (fun j ->
let pair = swap (i,j) in
if i <> j && not (Hashtbl.mem conflict_pairs pair) then
Hashtbl.add conflict_pairs pair ();
) (CudfAdd.resolve_vpkgs_int univ p.Cudf.conflicts)
) univ;
conflict_pairs