public sealed class KnowledgeGraphLayerIDSet 

{
  // get the active investigation view 
  var iv = KnowledgeGraphInvestigationView.Active;
  var serviceUri = iv.Investigation.ServiceUri;

  // build a dictionary of records
  string some_entity = "Entity_Type_Name";
  var dict = new Dictionary<string, List<long>>();
  //Each entry consists of the type name and corresponding lists of ids
  dict.Add(some_entity, new List<long>() { 1, 5, 18, 36, 78 });

  //Create the id set...
  var idSet = KnowledgeGraphLayerIDSet.FromDictionary(new Uri(serviceUri), dict);

  // select the records on the investigation view
  iv.SetSelectedRecords(idSet, SelectionCombinationMethod.New);
}

{
  // get the active investigation view 
  var iv = KnowledgeGraphInvestigationView.Active;

  // clear the selected records
  iv.ClearSelectedRecords();
}

{
  // get the active investigation view
  var iv = KnowledgeGraphInvestigationView.Active;

  await QueuedTask.Run(() =>
  {
    // get the investigation
    var inv = iv.Investigation;

    // get the set of selected records
    var idSet = iv.GetSelectedRecords();

    // view these records in a link chart
    var map = MapFactory.Instance.CreateLinkChart("myLinkChart", new Uri(inv.ServiceUri), idSet);
    ProApp.Panes.CreateMapPaneAsync(map);
  });
}

{
  await QueuedTask.Run(() =>
  {
    // get the selection set
    var sSet = map.GetSelection();

    // translate to an KnowledgeGraphLayerIDSet
    //  if the selectionset does not contain any KG entity or relationship records
    //    then idSet will be null  
    var idSet = KnowledgeGraphLayerIDSet.FromSelectionSet(sSet);
    if (idSet == null)
      return;

    // you can use the idSet to create a new linkChart
    //   (using MapFactory.Instance.CreateLinkChart)
  });
}