anchor.diff:  
         match conflicts with
         | Some (dep, _) ->
  -        System.Console.WriteLine (string (p, cs))
           yield Result.Error (Unresolvable dep.MinimumElement)
         | None ->
           for candidate in fetchCandidatesForConstraint sourceExplorer locations p c do
             match candidate with
             | Result.Error (Unresolvable d) ->
               unresolvableCores <- (unresolvableCores |> Map.add (Set [d]) (Unresolvable d))
  +
  +            System.Console.WriteLine "----------"
  +            for cores in unresolvableCores |> Map.keySet do
  +              cores |> Set |> System.Console.WriteLine
  +              System.Console.WriteLine "&&&&&"
  +            System.Console.WriteLine "----------"
  +
               yield Result.Error <| Unresolvable d
             | Result.Error (LimitReached d) ->
               if hadCandidate <> false
               then
                 underconstraintDeps <- (underconstraintDeps |> Set.add d)
  +              System.Console.WriteLine "----------"
  +              for cores in unresolvableCores |> Map.keySet do
  +                cores |> Set |> System.Console.WriteLine
  +                System.Console.WriteLine "&&&&&"
  +              System.Console.WriteLine "----------"
  +
               yield Result.Error <| LimitReached d
             | Result.Ok (_, (location, versions)) ->
               let! lock = sourceExplorer.LockLocation location
  
positive.code: 
          let! requested =
            resolver.PostAndAsyncReply (fun channel -> GetCandidates (constraints, (p, cs), locations, channel))
          let candidates = requested |> AsyncSeq.cache
  
          let fetched =
            candidates
            |> AsyncSeq.mapAsync(fun candidate -> async {
              match candidate with
              | Result.Error e ->
  
negative.code:   | Conflicts of Set<SearchStrategyError>
  
    type ResolutionRequest =
    | MarkBadPath of List<ResolutionPath> * PackageConstraint * SearchStrategyError * AsyncReplyChannel<Unit>
    | GetCandidates of Constraints * PackageConstraint * PackageSources * AsyncReplyChannel<AsyncSeq<Result<(PackageIdentifier * LocatedVersionSet), SearchStrategyError>>>
  
    type SearchStrategy = ISourceExplorer -> SolverState -> AsyncSeq<Result<PackageIdentifier * LocatedVersionSet, SearchStrategyError>>
  