if (!PlEngine.IsInitialized)
{
    String[] empty_param = { "" };
    PlEngine.Initialize(empty_param);
    // do some funny things ...
    PlEngine.PlCleanup();
} 
// program ends here

public void Demo_consult_pl_file_by_param()
{
    string[] ref_values = { "gloria", "melanie", "ayala" };
    Console.WriteLine("Demo_consult_pl_file_by_param");

    // Build a prolog source file (skip this step if you already have one :-)
    string filename = Path.GetTempFileName();
    StreamWriter sw = File.CreateText(filename);
    sw.WriteLine("father(martin, inka).");
    sw.WriteLine("father(uwe, gloria).");
    sw.WriteLine("father(uwe, melanie).");
    sw.WriteLine("father(uwe, ayala).");
    sw.Close();

    // build the parameterstring to Initialize PlEngine with the generated file
    String[] param = { "-q", "-f", filename };
    try
    {
        PlEngine.Initialize(param);
        Console.WriteLine("all child's from uwe:");
        using (PlQuery q = new PlQuery("father(uwe, Child)"))
        {
            int idx = 0;
            foreach (PlQueryVariables v in q.SolutionVariables)
            {
                Console.WriteLine(v["Child"].ToString());
                Assert.AreEqual(ref_values[idx++], v["Child"].ToString());
            }
        }
    }
    catch (PlException e)
    {
        Console.WriteLine(e.MessagePl);
        Console.WriteLine(e.Message);
    }
    finally
    {
        PlEngine.PlCleanup();
    }
} // Demo_consult_pl_file_by_param