In the C# test program I have

interface IParallelogram { ... }

class Parallelogram : IParallelogram
{
    private int height1;
    private int height2;

    ...
}

class Rectangle : IParallelogram
{
    private int height1;
    private int height2;

    ...
}

I store two instances of Parallelogram with (height1, height2) = (10, 10) and (20, 20), two instances of Rectangle with (10, 10) and (30, 30). Then the following queries return wrong results:

                IQuery q2 = objectContainer.Query();
                q2.Constrain(typeof(IParallelogram));
                IConstraint icon1 = q2.Descend("height1").Constrain(10);
                IConstraint icon2 = q2.Descend("height2").Constrain(10);
                IConstraint icon = icon1.And(icon2);
                IObjectSet os3 = q2.Execute();

returns an empty IObjectSet.

                IQuery q4 = objectContainer.Query();
                q4.Constrain(typeof(IParallelogram));
                IConstraint icon6 = q4.Descend("height1").Constrain(10).Not();
                IObjectSet os5 = q4.Execute();
 
returns all the four instances of IParallelogram.

The C# test program can be downloaded from https://svn.origo.ethz.ch/defcon/test_suites/SODA_Test.zip

In Eiffel for .NET applications, the developer only uses queries for interfaces because of multiple inheritance, so it is important to have SODA queries for interfaces work correctly.