using System;

public class Program

{

    public static void Main()

    {

        var test = new TestClass();

        Console.WriteLine("NullableBoolean2: " + (test.NullableBoolean2 == null ? "<null>" : test.NullableBoolean2.ToString()));

    }

}

​

public class TestClass

{

    public bool? NullableBoolean1 { get; set; }

    public bool? NullableBoolean2 { get { return !NullableBoolean1; } }

}