This works:

```
using System;
using ConstraintSet = System.Collections.Generic.Dictionary<System.String, double>;

namespace ConsoleApplication2
{
    class test
    {
        public ConstraintSet a { get; set; }
        public test()
        {
            a = new ConstraintSet();
        }
        static void Main(string[] args)
        {
            test abc = new test();
            Console.WriteLine("done");
        }
    }
}

```

This does not:

```
using System;
using ConstraintSet = System.Collections.Generic.Dictionary<System.String, double>;

namespace ConsoleApplication2
{
    class test
    {
        public ConstraintSet a { get { return a; } set { a = value; } }
        public test()
        {
            a = new ConstraintSet();
        }
        static void Main(string[] args)
        {
            test abc = new test();
            Console.WriteLine("done");
        }
    }
}

```

I get a stack overflow exception on a's setter in the second class and I do not know why. I cannot use the first form because it is not supported by the [Unity game engine](https://en.wikipedia.org/wiki/Unity_(game_engine)).